Dynamic and non-dynamic interspinous fusion implant and bone growth stimulation system

ABSTRACT

An interspinous fusion device is described. The interspinous fusion device includes a spacer member and an anchor member. The spacer member has a ring with two or more anchor assemblies projecting laterally from substantially opposite sides of the spacer member ring. The spacer member further has a first zip lock flange and a second zip lock flange, each of the first and second zip lock flanges extends transversely from the spacer member ring wherein each of the first and second zip lock flanges each comprises a series of teeth protruding from it. The anchor member has a ring with two or more anchor assemblies projecting laterally from substantially opposite sides of the anchor member ring. The anchor member further has a barrel extending transversely from the anchor member ring. The barrel comprises a first column of recesses adapted to mate with the teeth of the first zip lock flange and a second column of recesses adapted to mate with the teeth of the second zip lock flange. The spacer member is adapted to slide over the barrel of the anchor member such that the series of teeth of the first zip lock flange mates with the recesses in the first column of recesses of the barrel, and the series of teeth of the second zip lock flange mates with the recesses in the second column of recesses of the barrel to secure the spacer member to the anchor member.

RELATED APPLICATIONS

This application claims priority from the following U.S. ProvisionalPatent Applications, all of which are incorporated herein by referencein their entirety: 61/625,626 filed Apr. 17, 2012, 61/640,163 filed Apr.30, 2012, 61,674,807 filed Jul. 23, 2012, 61/716,779 filed Oct. 22,2012, and 61/778,627 filed Mar. 13, 2013.

BACKGROUND

This invention relates generally to the field of spinal fusion surgeryand more specifically to interspinous fusion implants and bone growthstimulation systems.

In 1986, the first interspinous device was introduced in Europe. It wasthe first dynamic stabilization system and consequently has the longesthistory at present. The device's original design was a titanium blockerthat was inserted between adjacent processes and held in place with apolyester band wrapped around the spinous process above and below theblocker. After this first-generation device showed positive results, asecond generation of interspinous implants were developed. The primarychange was in the material used for the interspinous spacer. It waschanged from titanium to polyetheretherketone (PEEK), a strong,plastic-like polymer that has more elasticity and is therefore lessrigid than the previously used material. The implant has notches thatfit the physiological shape of the lumbar spine.

Several devices currently exist that can be inserted between the spinousapophysis. Said devices have their antecedents in bone grafts placedbetween the spines more than fifty years ago. They were H-shaped andplaced so that their ends surrounded the spines and their horizontalpart was located between said spines in order to diminish the mobilityamong the vertebrae and achieve its final fusion. Likewise, there existantecedents related to vertebral fusion which used different bow types,mostly metal bows to be linked to the spinous apophysis so that theybecome immobilized.

Newer technologies also exist that prohibit both flexion and compressionbetween successive spinous processes. These devices are inserted betweenthe spinous processes and contain barrel-like objects that maintain aspace between the spinous processes thus prohibiting compression, whilealso containing successive plates with spikes that bore into successivespinal processes thus prohibiting flexion.

The problem with all of the known devices is associated with wear andtear. Interspinous implants are meant to be long-term solutions thatremain implanted for preferably the life of the subject who is treatedwith them. With life expectancy of people in developed countriesexceeding 80 years of age and many people now living actively into their90s, these devices must maintain their functional integrity and must notfail for decades. Unfortunately, many of the current implants are proneto failure due to their design. What is needed are implants that remainfirmly in place and maintain their functional integrity and are unlikelyto suffer a mechanical failure for the life of the recipient of theimplants.

Another problem is that current implants have barrels that do not allowfor small amounts of flexion or compression between spinous processes.Yet, the human body is dynamic and the vertebral column is adapted toallow flexion and compression between spinous processes. This isnecessary to protect adjacent discs from degeneration. Thus, onceimplanted, prior devices do not allow for any relative movement betweensuccessive spinous processes. What's needed are devices that allow forsmall amounts of controlled flexion and compression between successivespinous processes while maintaining their functional integrity and notbeing prone to failure.

Yet another problem is that most implants that prohibit compression andflexion require set screws and drivers to fix the components of theimplants to the bone and fix the parts of the implant firmly in placerelative to one another. This requires extra space to work in order toscrew and unscrew. In addition, the single point of a set screw istasked with maintaining the orientation of the parts of the device foras long as the device is in the body. All of the forces that pull andpush the parts of the device toward and away from one another convergeon the single set screw point that is tasked with maintaining thefunctional integrity of the device and prevent its failure. What isneeded are devices that remain their functional integrity for longperiods of time and are not prone to the limitations of using setscrews.

Also lacking in the field are interspinous implants adapted for thecervical spine that don't require pedicle screws and rods or fusionplates and are modular and adaptable to the specific patient anatomy.

Current devices are also dumb in the sense that they have no capabilityto record local data and transmit it to an external device where thedata can be processed and analyzed by healthcare professionals as partof ongoing patient care. What's needed are interspinous implants thatcan store and/or obtain information about the implant and itsenvironment, such as the stresses on the implant, whether the implanthas moved over time, whether the parts of the implant have becomedislodged from one another or have loosened, the date the implant wasimplanted, and patient identification information, and so on. This willallow for healthcare providers to better manage the care of patients whohave such devices implanted in the spinal column without having toresort to surgical intervention to determine the status of the implants.

Current interspinous devices lack any ability to promote bone growth.What's needed are orthopedic implants that can be activated by anexternal device to stimulate and promote bone growth and fusion whenfusion is desired. No such devices exist at the present time, and yetthey are needed to promote healing and reduce the time it takes forfusion between successive vertebrae to occur.

SUMMARY

One object of the invention is to provide a better interspinous implantthat allows controlled, dynamic movement of vertebrae until fusionoccurs while using a one-step, easy to install friction-lock mechanismwith a zipping action. This type of locking mechanism eliminates theneed for screws and screw drivers for securing implant components tobone.

Another object of the invention is to provide a device in whichloosening of screws or migration of the implant cannot occur since themechanism is a compressible friction-lock system with a zipping actionand multiple engagement points.

Another object of the invention is to provide a spinal fusion implantthat is dynamic, therefore preventing spinal discs at the fusion sitefrom being completely immobile and allowing some controlled movementbetween successive interspinous processes.

Another object of the invention is to provide a spinal fusion implantthat is dynamic, therefore allowing controlled load sharing and movementof discs above and below fusing vertebrae, thus protecting discs aboveand below fusing vertebras from degenerating over time as a result ofthe fusion.

Yet another object of the invention is to provide a spinal fusionimplant that can be implanted in a downward direction to attach in aparallel fashion to upward protruding walls of spinous processes.

Still yet another object of the invention is to provide a spinal fusionimplant that can be implanted in an upward direction to attach to theangled root of spinous processes.

Another object of the invention is to provide a spinal fusion implantthat can be implanted in an upward or downward direction, depending onquality and bone volume required for the implantation.

Another object of the invention is to provide a spinal fusion implantwhich requires a small incision for implantation for reduced trauma tothe patient.

A further object of the invention is to provide a spinal fusion implantthat can be safely adjusted and compressed or decompressed safely whennecessary any time after completion of surgery thru a small percutaneousopening.

Still yet another objective of the invention is to provide a dynamicspinal fusion implant where the dynamic feature of the implant can belocked when needed, and the locking can be fully reversed when necessaryso that the implant becomes dynamic again, i.e. an implant that can bedynamic or non-dynamic depending on the need of the patient at the time.

In various embodiments, the spinal fusion implant devices describedherein can be manufactured from implantable metal, plastic or reinforcedplastic. They can also be manufactured from metal reinforced plasticmaking the implant body conductive to carry electrical signals orcurrent, or from entirely conductive material to carry electricalsignals or current. They can also be manufactured with a surface made ofpyrolitic carbon over a graphite core.

In one embodiment, the devices described herein can carry electricalsignals or current for the promotion or stimulation of bone growth. Suchdevices can serve as electrical or magnetic bone growth stimulators. Inanother embodiment, they can be activated to emit magnetic energy byreceiving wireless signals that activate them to emit magnetic energy.

Another object of the invention is to provide a spinal fusion implantbuilt together with a micro-electro-mechanical system chip (or MEMSchip) for the transmission of clinically useful patient information toan external reader. Such a chip can also continuously monitor a patientafter surgery or be activated to gather local data and save it in memoryor transmit it upon obtaining the data.

In one embodiment, an interspinous fusion device is described. Theinterspinous fusion device includes a spacer member and an anchormember. The spacer member has a ring with two or more anchor assembliesprojecting laterally from substantially opposite sides of the spacermember ring. The spacer member further has a first zip lock flange and asecond zip lock flange, each of the first and second zip lock flangesextends transversely from the spacer member ring wherein each of thefirst and second zip lock flanges each comprises a series of teethprotruding from it. The anchor member has a ring with two or more anchorassemblies projecting laterally from substantially opposite sides of theanchor member ring. The anchor member further has a barrel extendingtransversely from the anchor member ring. The barrel comprises a firstcolumn of recesses adapted to mate with the teeth of the first zip lockflange and a second column of recesses adapted to mate with the teeth ofthe second zip lock flange. The spacer member is adapted to slide overthe barrel of the anchor member such that the series of teeth of thefirst zip lock flange mates with the recesses in the first column ofrecesses of the barrel, and the series of teeth of the second zip lockflange mates with the recesses in the second column of recesses of thebarrel to secure the spacer member to the anchor member.

In accordance with another embodiment, an interspinous fusion device hasa first member and a second member. The first member has a set of firstlateral spinous process attachment arms and a first locking membertransverse to the first lateral spinous process attachment arms, whereinthe locking member comprises a row of zip-locking teeth. The secondmember comprising a set of second lateral spinous process attachmentarms and a second locking member transverse to the second lateralspinous process attachment arms, wherein the second locking membercomprises a row of zip-locking recesses that are sized to receive thezip-locking teeth of the first member and wherein the first and secondmembers can be reversibly locked together when they mate.

In accordance with another embodiment, an orthopedic implant isdescribed. The orthopedic implant has a surface made of pyroliticcarbon, wherein the orthopedic implant is capable of receiving awireless signal from an external transmitter and emitting a magneticfield that stimulates bone growth in an area adjacent the implant.

In accordance with another embodiment, a kit for orthopedic surgicalprocedures is provided. The kit includes one or more orthopedicimplants. The one or more orthopedic implants have a surface made ofpyrolitic carbon. The orthopedic implants are capable of receiving awireless signal from an external transmitter and emitting a magneticfield that stimulates bone growth in an area adjacent the implant. Thekit also includes natural or synthetic bone matrix and a wireless signaltransmitter that is capable of transmitting a wireless signal to the oneor more orthopedic implants.

In yet another embodiment, a cervical implant is described. The cervicalimplant has a first barrel, a second barrel, and one or more plates thatconnect the first barrel to the second barrel. The first barrel has oneor more hooks engaged to it, wherein the one or more hooks are movablerelative to the first barrel. The second barrel also has one or morehooks engaged to it, wherein the one or more hooks of the second barrelare movable relative to the second barrel. The hooks can be rotatedconcentrically about the barrels.

In accordance with another embodiment, a modular cervical implant systemis described. The modular cervical implant system has a first barrel, asecond barrel, a first pair of plates, one or more additional barrelsand a second or more pair of plates corresponding to the number ofadditional barrels. The first barrel has one or more hooks engaged toit, wherein the one or more hooks are movable relative to the firstbarrel. The second barrel also has one or more hooks engaged to it,wherein the one or more hooks of the second barrel are movable relativeto the second barrel. The first pair of plates connect the first barrelto the second barrel. The one or more additional barrels each also hasone or more hooks engaged to it, wherein the one or more hooks of theone or more additional barrels are movable relative to its respectivebarrel. Each pair of the second or more pair of plates connects one ofthe additional barrels to the first or the second barrel or to anotherof the additional barrels.

In accordance with another embodiment, an interspinous fusion system isdescribed. The interspinous fusion system has a number of interspinousfusion devices and a pair of rods that connects the interspinous fusionsdevices to one another. The first of the pair of rods can be connectedto a first member of each of the series of interspinous fusion devicesand the second of the pair of rods can be connected to a second memberof each of the series of interspinous fusion devices.

Other objects and advantages of the present invention will becomeapparent from the following descriptions, taken in connection with theaccompanying drawings, wherein, by way of illustration and example,various embodiments of the present invention are disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings constitute a part of this specification and includeexemplary embodiments to the invention, which may be embodied in variousforms. It is to be understood that in some instances various aspects ofthe invention may be shown exaggerated or enlarged to facilitate anunderstanding of the invention.

FIG. 1 is an exploded isometric view of an interspinous implant inaccordance with one embodiment.

FIG. 2 is an exploded isometric view of an interspinous implant inaccordance with another embodiment.

FIG. 3 is an exploded isometric view of an interspinous implant inaccordance with yet another embodiment.

FIG. 4 is an exploded isometric view of an interspinous implant inaccordance with yet another embodiment.

FIG. 5 is an isometric view of the interspinous implant depicted in FIG.4 in its assembled state.

FIG. 6 is a three dimensional illustration of two of the interspinousimplants depicted in FIG. 4 implanted in a successively stackedconfiguration.

FIG. 7 is an isometric view of an interspinous implant in accordancewith another embodiment and a three-dimensional illustration of saidimplant as it is implanted in the lower vertebral column adjacent thesacrum.

FIG. 8a is a side view of multiple successive interspinous implantsimplanted in the lumbar region of the vertrebral column in accordancewith one embodiment in which the multiple implants are connected by arod.

FIG. 8b is an isometric view of multiple successive interspinousimplants connected to one another in a stack configuration by rods inaccordance with one embodiment.

FIG. 8c is an exploded view of the multiple successive interspinousimplants depicted in FIG. 8 a.

FIG. 8d is an exploded isometric view of the rod and nub assemblydepicted in FIG. 8 c.

FIG. 8e is another isometric view of the rod and nub assembly depictedin FIG. 8d in a coupled state.

FIG. 8f provides several views of the nub depicted in FIGS. 8c -8 e.

FIG. 9 is an exploded isometric view of an interspinous implant withconnecting rods in accordance with another embodiment.

FIG. 10a is a top view of a modular cervical interspinous implant systemin accordance with one embodiment.

FIG. 10b is a side view of the modular cervical interspinous implantsystem depicted in FIG. 10 a.

FIG. 10c is an isometric view of the modular cervical interspinousimplant system depicted in FIG. 10 a.

FIG. 10d is an isometric view of the modular cervical interspinousimplant system depicted in FIG. 10a when implanted in the cervicalregion of the vertebral column.

FIG. 10e is a top view of the modular cervical interspinous implantsystem depicted in FIG. 10a when implanted in the cervical region of thevertebral column.

FIG. 10f provides various views of a cervical interspinous implantassembly in accordance with one embodiment.

FIG. 11 is an exploded isometric view of an interspinous implant inaccordance with another embodiment.

FIGS. 12a-12f are various views of an interspinous implant in accordancewith another embodiment. FIG. 12A is an isometric view. FIG. 12b is atop view. FIG. 12c is a view of one end of the device, and FIG. 12d is aview of the opposite end of the device. FIG. 12e is a view of the rightside of the device, and FIG. 12f is a view of the left side of thedevice.

FIGS. 13a-13f are various views of the left component of theinterspinous implant depicted in FIGS. 12a-12f . FIG. 13a is anisometric view. FIG. 13b is a view of the left side of the component.FIG. 13c is a bottom view of the component. FIG. 13d is a top view ofthe component. FIG. 13e is a view of one end of the component, and FIG.13f is a view of the opposite end of the component.

FIGS. 14a-14f are various views of the right component of theinterspinous implant depicted in FIGS. 12a-12f . FIG. 14a is anisometric view. FIG. 14b is a view of the left side of the component.FIG. 14c is a bottom view of the component. FIG. 14d is a top view ofthe component. FIG. 14e is a view of one end of the component, and FIG.14f is a view of the opposite end of the component.

FIG. 15 is an illustration of a bone growth stimulation system.

DETAILED DESCRIPTION

Exemplary embodiments of the invention are shown in the accompanyingfigures. In accordance with one embodiment, FIG. 1 shows one embodimentof a dynamic interspinous implant 1 made of two separate butinterlocking components, male component 10 and female component 20. Thetwo components 10 and 20 are shown in an exploded view in FIG. 1, butthey are locked together when implanted as described further herein.Male component 10 has two arms projecting up and down respectively froma central loop 6. The first arm 5 a projects in an upward or superiordirection from loop 6, and the second arm 5 b projects in a downward orinferior direction from loop 6. Both arms 5 a and 5 b are integrallyformed in a unibody construction with loop 6 and are connected to oneanother through loop 6. The lower portion 7 of arm 5 a is in closeproximity to the upper portion 8 of arm 5 b. In its resting state whenno forces are exerted on male component 10, the distance between lowerportion 7 and upper portion 8 is between about 1.0 mm and 10.0 mm, sothat the distance can be about 1.0 mm, 1.5 mm, 2.0 mm, 2.5 mm, 3.0 mm,3.5 mm, 4.0 mm, 4.5 mm, 5.0 mm, 5.5 mm, 6.0 mm, 6.5 mm, 7.0 mm, 7.5 mm,8.0 mm, 8.5 mm, 9.0 mm, 9.5 mm, 10.0 mm, or 10.5 mm. The loop 6 issemi-rigid and can be compressed or flexed. When the loop 6 is squeezedarms 5 a and 5 b are compressed toward each other. At full compression,lower portion 7 comes into contact with upper portion 8 so that nofurther compression can be achieved. Arms 5 a and 5 b have compressionrecesses 24 a and 24 b. Compression recesses 24 a and 24 b receive acompression tool that is used to squeeze male component 10 and femalecomponent 20 toward one another. Although not visible in FIG. 1, femalecomponent 20 has corresponding compression recesses on outer sides ofarms 11 a and 11 b that receive a compression tool as well. The innersides of arms 5 a and 5 b form a surface having serrated teeth 22 a and22 b respectively to fixedly engage with bone of the spinous process.Alternatively, the inner sides of arms 5 a and 5 b can have spikes thatengage the bone. Projecting transversely from the inner side of thelower portion 7 is a first locking barrel 28 a that corresponds andmates with zip-lock recess 23 a of female component 20. Projectingtransversely from the inner side of the upper portion 8 is a secondlocking barrel 28 b that corresponds and mates with zip lock recess 23 bof female component 20. Barrels 28 a and 28 b have bone graft windows 27a and 27 b respectively. These windows allow for bone to grow throughthem and allow for adjacent vertebrae to fuse with one another when theinterspinous implant 1 is implanted between spinous processes.

Across from male component 10 is female component 20. Female component20 has two arms projecting up and down respectively from a central loop9. The first arm 11 a projects in an upward or superior direction fromloop 9, and the second arm 11 b projects in a downward or inferiordirection from loop 9. Both arms 11 a and 11 b are integrally formed ina unibody construction with loop 9 and are connected to one anotherthrough loop 9. The lower portion 17 of arm 11 a is in close proximityto the upper portion 18 of arm 11 b. Just as with male component 10, inits resting state when no forces are exerted on female component 20, thedistance between lower portion 17 and upper portion 18 is between about1.0 mm and 10.0 mm, so that the distance can be about 1.0 mm, 1.5 mm,2.0 mm, 2.5 mm, 3.0 mm, 3.5 mm, 4.0 mm, 4.5 mm, 5.0 mm, 5.5 mm, 6.0 mm,6.5 mm, 7.0 mm, 7.5 mm, 8.0 mm, 8.5 mm, 9.0 mm, 9.5 mm, 10.0 mm, or 10.5mm. The loop 6 is semi-rigid and can be compressed or flexed. When theloop 9 is squeezed arms 11 a and 11 b are compressed toward each other.At full compression, lower portion 17 comes into contact with upperportion 18 so that no further compression can be achieved. Thus, loop 6is opposite to and corresponds with loop 9. Arm 11 a is opposite to andcorresponds with arm 5 a. Arm 11 b is opposite to and corresponds witharm 5 b. The inner sides of arms 11 a and 11 b form a surface havingserrated teeth 21 a and 21 b respectively to fixedly engage with bone ofthe spinous process. Alternatively, the inner sides of arms 11 a and 11b can have spikes that engage the bone.

The juncture between the lamina and the spinous process is curved. Thespinous process itself is not uniform in thickness and perfectly flat onboth sides. It tends to bow in and out. To account for the curvature ofthe spinous process and the lamina, the inner surface of the loops 6 and9 can be at an angle relative to the arms 5 a and 5 b and 11 a and 11 brespectively as shown in FIG. 1. Thus, when the serrated teeth 21 a, 21b, 22 a, and 22 b have dug into the bone, the inner surfaces of theloops 6 and 9 rest flush against the outer sides of the successivespinous processes.

Male component 10 and female component 20 mate with one another in thefollowing manner. As the two are brought toward one another, barrels 28a and 28 b slide into zip-lock recesses 23 a and 23 b respectively.Inside of recesses 23 a and 23 b are zip-locking teeth 26 (each recesscan have the zip-locking teeth although they are only visible in recess23 a in the view shown in FIG. 1). Zip locking teeth 26 can encircle theentire inner radius of the recess or they can form an arc that does notcompletely encircle the recess as shown in FIG. 1. In yet anotherembodiment, there can be two or multiple sets of teeth opposing eachother within the recesses 23 a and 23 b. Teeth 26 protrude out from thesurface of the recesses 23 a and 23 b toward the center of each recess.Each tooth of the series of zip lock teeth 26 can form a top angledsliding face and a back locking ridge. The sliding face is angled toallow teeth 26 to slide forward and mate with the zip lock holes 25 thatare on the surface of the barrels 28 a and 28 b. The back locking ridgeof teeth 26 can form a substantially 90° angle (or alternatively anacute angle) with the inner surface of the recesses 23 a and 23 b.

When the barrels 28 a and 28 b slide into recesses 23 a and 23 b, theteeth 26 slide over the outer surface of the barrels 28 a and 28 b andinto the holes 25 on the barrel that are sized and shaped to receive theteeth 26. Only three holes 25 are shown in FIG. 1, but there can be morethan that number of holes or fewer. In one embodiment, there are 4holes. In other embodiments, there are 5, 6, 7, 8, 9, 10 or more holeson each barrel to receive between 1 and 10 teeth from each zip-lockrecess 23 a and 23 b. When teeth 26 engage with holes 25, the malecomponent 10 and female component 20 become locked to one another. Thedistance between the male component 10 and female component 20 can beadjusted by sliding the barrels 28 a and 28 b further into recesses 23 aand 23 b.

Male and female components 10 and 20 mate with one another to form asingle interspinous implant 1 that not only separates two adjacentspinous processes from one another at a predetermined distance, butkeeps them locked with respect to one another as a result of thepenetration of the spinous processes by the serrated teeth 21 a, 21 b,22 a, and 22 b. The opposing loops 6 and 9 prevent extension betweenadjacent spinous processes, while the serrated teeth 21 a, 21 b, 22 a,and 22 b prevent flexion between two adjacent spinous processes, exceptfor a limited amount due to the dynamic nature of the interspinousimplant 1 resulting from the flexible loops 6 and 9 that allow the lowerportions 7 and 17 and upper portions 8 and 18 to move toward and awayfrom one another respectively.

In one method of implantation, the assembled interspinous implant 1 canbe inserted between two spinous processes of adjacent vertebrae in ananterior to posterior direction after severing spinous ligaments toremove them from the path of implantation. In another method ofimplantation, no spinous ligaments are severed and the male and femalecomponents 10 and 20 are separated and can each individually be insertedfrom opposing lateral directions toward each other anterior to theundisturbed spinous ligaments. In either case, once the two componentsare on opposite sides of successive spinous processes, male and femalecomponents 10 and 20 are squeezed or pushed toward one another with acompression tool until the serrated teeth 21 a and 22 a penetrate theouter sides of a superior spinous process while the serrated teeth 21 band 22 b penetrate the outer sides of the spinous process just inferiorto the superior spinous process penetrated by the teeth 21 a and 22 a.With the penetration of the teeth the interspinous implant 1 prohibitsuncontrolled and excessive extension (as a result of the flexible loops6 and 9 abutting the inner spinous processes) and flexion (as a resultof the anchoring by serrated teeth 21 a, 21 b, 22 a, and 22 b). Thus,the implant 1 allows for a limited amount of dynamic movement betweenthe adjacent spinous processes due to the flexibility of the loops 6 and9 and the distance between the lower 7 and 17 and upper 8 and 18portions respectively. The amount of movement between the adjacentspinous processes is controlled by the flexibility of the loops 6 and 9.

FIG. 2 shows an embodiment of a nondynamic interspinous implant 2. Thisimplant is similar to implant 1, but rather than a disjoined pair ofloops 6 and 9, it has a pair of opposing cylindrical barrel regions 56and 59 on opposing male and female components 51 and 50 respectively.The barrel regions 56 and 59 can be semi-rigid and allow for somedistortion thus allowing for some amount of controlled flexion andextension between spinous processes, or they can be rigid and not allowany distortion or flexing. Male component 51 contains a lateral plate 45with a process fixation region 47 that allows opposite ends of the plate45 to be secured to successive spinous processes. Likewise femalecomponent 50 has a lateral plate 41 with a process fixation region 48that allows opposite ends of the plate 41 to be secured to the otherside of the same successive spinous processes to which the fixationregion 47 is secured. Each of plates 45 and 41 has transverse inwardlyfacing spikes 40 that can penetrate into bone. The spikes 40 can bereplaced with serrated teeth such as those of implant 1. The insidesurfaces of the plates 41 and 45 can be angled as shown in FIG. 2 tomatch the outer walls of the spinous processes. Male component 51 has aseat 42 a that nests with counter-seat 42 b of female component 50. Seat42 a is curved to match the curve of counter seat 42 b and nestsconcentrically with counter seat 42 b to form a bone graft retainer.Bone graft material is packed onto bone graft retainer, which preventsthe bone graft material from migrating into the spinal canal duringsurgical implantation. The bone graft material aids in the fusionprocess between successive spinous processes. The openings ofcylindrical barrel regions 56 and 59 allows for insertion of the bonegraft material after implant 2 has been implanted and fixed in placebetween two successive spinous processes. The connection between themale and female components 51 and 50 respectively is the same as implant1 of FIG. 1, and implant 2 is implanted in the same manner as implant 1.

FIG. 3 shows another embodiment of a dynamic interspinous implant 3 madeof two separate but interlocking components, male component 61 andfemale component 60. The two components 61 and 60 are shown in anexploded view in FIG. 3, but they are locked together when implanted asdescribed further herein. Female component 60 has two arms projecting upand down respectively from a central flex joint 71. The first arm 60 aprojects in an upward or superior direction from flex joint 71, and thesecond arm 60 b projects in a downward or inferior direction from flexjoint 71. Both arms 60 a and 60 b are integrally formed in a unibodyconstruction with one another and are connected to one another at flexjoint 71. A gap 73 is formed between first arm 60 a and second arm 60 b.In its resting state when no forces are exerted on male component 61,the size of gap 73 is between about 1.0 mm and 10.0 mm, so that the gap73 can be about 1.0 mm, 1.5 mm, 2.0 mm, 2.5 mm, 3.0 mm, 3.5 mm, 4.0 mm,4.5 mm, 5.0 mm, 5.5 mm, 6.0 mm, 6.5 mm, 7.0 mm, 7.5 mm, 8.0 mm, 8.5 mm,9.0 mm, 9.5 mm, 10.0 mm, or 10.5 mm. Flex joint 71 allows arms 60 a and60 b to splay apart for a controlled and limited distance. This allowsgap apex 71 a to close entirety or to grow. The gap apex 71 a can growby no more than triple its resting distance. For example, if gap apex 71a at rest is 3.0 mm, it can spread to no more than about 9.0 mm. Inanother embodiment, gap apex 71 a can grow by no more than between about1.0 mm and about 10 mm, and in one embodiment, no more than by about 5.0mm. This allows for a limited amount of controlled flexion and extensionbetween the adjacent spinous processes that are separated by the implant3. At maximum compression (during extension of the spinal column), thereis no gap between the first and second arms 60 a and 60 b at gap apex 71a, i.e., the gap is closed.

Arms 60 a and 60 b have compression recesses 70 a and 70 b. Compressionrecesses 70 a and 70 b receive a compression tool that is used tosqueeze male component 60 and female component 61 toward one another.Although not visible in FIG. 3, male component 61 has correspondingcompression recesses on outer sides of arms 61 a and 61 b that receive acompression tool as well. The inner sides of arms 60 a and 60 b havespikes 62 that extend in a transverse direction toward male component 61and fixedly engage with bone of the spinous process. The inner sides ofarms 61 a and 61 b of male component 61 also has spikes 62 that extendin a transverse direction toward the female component 60. Alternatively,the inner sides of arms 60 a and 60 b and 61 a and 61 b respectively canhave serrated teeth that engage the bone instead of or in addition tospikes 62. Female component 60 and male component 61 also have holes 66on the corners of arms 60 a and 60 b. These holes 66 receive surgicalthread or metal wire that is used to loop around spinous processes foradditional stability and security.

Like female component 60, male component 61 has two arms projecting upand down respectively from a central flex joint 72. The first arm 61 aprojects in an upward or superior direction from flex joint 72, and thesecond arm 61 b projects in a downward or inferior direction from flexjoint 72. Both arms 61 a and 61 b are integrally formed in a unibodyconstruction with one another and are connected to one another at flexjoint 72. A gap 74 is formed between first arm 61 a and second arm 61 b.In its resting state when no forces are exerted on male component 61,the size of gap 74 is between about 1.0 mm and 10.0 mm, so that gap 74can be about 1.0 mm, 1.5 mm, 2.0 mm, 2.5 mm, 3.0 mm, 3.5 mm, 4.0 mm, 4.5mm, 5.0 mm, 5.5 mm, 6.0 mm, 6.5 mm, 7.0 mm, 7.5 mm, 8.0 mm, 8.5 mm, 9.0mm, 9.5 mm, 10.0 mm, or 10.5 mm. Flex joint 72 allows arms 61 a and 61 bto splay apart for a controlled and limited distance. This allows theapex of gap 74 to close entirety or to grow. The apex of gap 74 can growby no more than triple its resting distance. For example, if the apex ofgap 74 at rest is 3.0 mm, it can spread to no more than 9.0 mm. Inanother embodiment, the apex of gap 74 can grow by no more than between1.0 mm and 10 mm, and in one embodiment, no more than by 5.0 mm. Thisallows for a limited amount of controlled flexion and extension betweenthe adjacent spinous processes that are separated by implant 3. Atmaximum compression (during extension of the spinal column), there is nogap between the first and second arms 61 a and 61 b at the apex of gap74, i.e., the gap is closed. All of this corresponds with theflexibility of the female component 60. Thus, the properties of gap 73and gap 74 can be the same, so that the gap distance, splaying abilityand maximum splaying distance are the same for gaps 73 and 74.

Male component 61 has a bone abutment 69 that is formed by two opposingarched abutments 63 a and 63 b with the flat sides 63 x (or bases of thearches) adjacent each other and the arched sides 63 y directed away fromeach other. Arched superior abutment 63 a extends from the inner side ofarm 61 a and is transverse to arm 61 a and substantially perpendicularto arm 61 a. Arched inferior abutment 63 b extends from the inner sideof arm 61 b and is transverse to arm 61 b and substantiallyperpendicular to arm 61 b. Flat sides or bases 63 x of each of archedabutments 63 a and 63 b are parallel to gap 74 and face each other.Where the arch 63 y and base 63 x of each of arched abutments 63 a and63 b meet at the top is a column of zip-lock teeth 63 c and 63 drespectively. Each of columns 63 c and 63 d of zip-lock teeth is shownas extending the entire length of the base of each arched abutment 63 aand 63 b respectively. However, the columns may not extend the entirelength of the arched abutments 63 a and 63 b. For example, in oneembodiment, the columns of teeth 63 c and 63 d may start at the distalend of the arched abutments 63 a and 63 b and extend only part of theway (e.g., ¾ of the way, ⅔ of the way, ½ of the way, ⅓ of the way, or ¼of the way), toward the arms 61 a and 61 b respectively, and not extendall the way to the arms 61 a and 61 b. In one embodiment, the archedabutments 63 a and 63 b each has only one set of columns of zip-lockteeth as shown in FIG. 3. In another embodiment (not shown), where thearch 63 y and base 63 x of each of arched abutments 63 a and 63 b meetat the bottom is another column of zip-lock teeth on each of the archedabutments 63 a and 63 b that are on the opposite side of the abutmentsfrom columns 63 c and 63 d.

Each of the arched abutments 63 a and 63 b slides into a correspondinglyshaped opening 68 a and 68 b respectively in female component 60. Archedsuperior abutment 63 a slides into opening 68 a that forms an archedtunnel that receives the arched abutment 63 a. Arched inferior abutment63 b slides into opening 68 b that forms an arched tunnel that receivesthe arched abutment 63 b. The distal ends of each of arched abutments 63a and 63 b slide into their corresponding openings 68 a and 68 b on theinner side of female component 60, and they slide through the openingsand out of the openings 68 a and 68 b respectively on the outer side offemale component 60. On the other side of the openings 68 a and 68 b arelatches 67 a and 67 b respectively. The latches are biased outward awayfrom the outer side of the female component 60. As the abutments 63 aand 63 b slide through openings 68 a and 68 b, the columns of teeth 63 cand 63 d slide past latches 67 a and 67 b respectively. The teeth areangled backwards so that the latches slide over the angled top sides ofthe teeth. However, latches 67 and 67 b will catch against the backsides of the teeth and prevent the abutments 63 a and 63 b from slidingback out of the openings 68 a and 68 b. In order to release malecomponent 61 from female component 60, latches 67 a and 67 brespectively can be rotated around a screw so that latches 67 a and 67 bare rotated away from the teeth of the columns 63 c and 63 d. Oncelatches 67 a and 67 b are rotated away from the teeth and no longercatch against the back side of the teeth, the male component 61 can bepulled back out of the female component 60. This zip-lock mechanismallows for a secure coupling between the male 61 and female 60components. Another benefit is that a set screw is not required, nor isthere a requirement for additional tools to secure the two components toone another. Simply sliding the male component 61 into the femalecomponent 60 results in a lock between the two components withoutadditional handling.

The implant 3 is dynamic, but it has a feature that can be used to makeit non-dynamic. Each of abutments 63 a and 63 b have one or more notches65 (3 shown in FIG. 3) on their arch side 63 y. Metal rings can befitted around the abutments 63 a and 63 b that fit into the notches 65.The rings prevent the abutments 63 a and 63 b from spreading apart andaway from each other. The abutments 63 a and 63 b are attached (orformed integrally) to arms 61 a and 61 b respectively. As a result ofthe abutments not being able to spread away from each other, arms 61 aand 61 b are prevented from splaying away from each other and allowinggap 74 to widen. Also, when the distal ends of the abutments are in theopenings 68 a and 68 b, arms 60 a and 60 b are prevented from splaying.This is because there is a tight fit between the outer surface ofabutments 63 a and 63 b and the inner surface of their respectiveopenings 68 a and 68 b, and when the abutments are prevented fromsplaying or spreading, this prevents the arms 60 a and 60 b fromsplaying, effectively locking the gap 71 a at a fixed maximum distance.The rings do not prevent gaps 71 a and 74 from closing, thus the implantremains partly dynamic in that it allows for some extension between thespinous processes. In other words, when the spinal column undergoesextension, the spinous processes are squeezed towards each other andthey squeeze the abutments 63 a and 63 b toward each other as a resultof the superior process being forced downward against abutment 63 awhile abutment 63 b is then forced against the inferior spinous process,thus causing the abutments 63 a and 63 b to be forced towards each otherclosing gaps 73 and 74. In another embodiment, in which the implant canbe made completely non-dynamic, i.e., preventing both flexion andcompression, rigid connector 76 a on female component 60 can be used tolock the two arms 60 a and 60 b with respect to one another and thusprevent any movement between the two arms 60 a and 60 b. This will lockthe gap 71 a at a fixed distance. Likewise, rigid connector 76 b on malecomponent 61 can be used to lock the two arms 61 a and 61 b with respectto one another and thus prevent any movement between the two arms 61 aand 61 b. This will lock gap 74 at a fixed distance. Once connector 76 ais connected to both the arms 60 a and 60 b across gap 71 a, it forms arigid connection lock between arms 60 a and 60 b. Thus, arms 60 a and 60b can no longer move with respect to one another, and gap 73 betweenthem becomes fixed. Likewise, once connector 76 b is connected to botharms 61 a and 61 b across gap 74, it forms a rigid connection lockbetween arms 61 a and 61 b. Thus, arms 61 a and 61 b can no longer movewith respect to one another, and gap 74 between them becomes fixed. Inthis way, the arms cannot splay apart or come together. Thus, implant 3becomes non-dynamic and prevents flexion and extension between adjacentspinous processes. The abutments 63 a and 63 b prevent extension andspikes 62 prevent flexion.

In one method of implantation, the assembled interspinous implant 3 canbe inserted between two spinous processes of adjacent vertebrae in ananterior to posterior direction after severing spinous ligaments toremove them from the path of implantation. In another method ofimplantation, no spinous ligaments are severed and the male and femalecomponents 61 and 60 are separated and can each individually be insertedfrom opposing lateral directions toward each other anterior to theundisturbed spinous ligaments. Once the implant 3 is inserted betweensuccessive spinous processes, the male component 61 and female component60 are brought toward each other so that the abutments 63 a and 63 bslide into openings 68 a and 68 b respectively. The two components aresqueezed toward each other until the inner sides of the arms of eachcomponent come into contact with the outer side of the adjacent spinousprocesses. Arms 61 a and 60 a come into contact with the superiorspinous process while arms 61 b and 60 b come into contact with thespinous process just inferior to the spinous process contacted by arms61 a and 60 a. The two components 60 and 61 are further squeezedtogether as the teeth of the zip-lock columns 63 c and 63 d engage withthe latches 67 a and 67 b, and the latches 67 a and 67 b catch againstthe teeth and lock the male component 61 to the female component 60 andprevent the two from coming apart. The two components (male 61 andfemale 60) are further squeezed together until spikes 62 penetrate thebone on the outer sides of the successive spinous processes and form atight grip on the two successive spinous processes. When that happens,the implant is securely in place with no need for further screwing. Iffusion is the required result, then the arms can be locked together asdescribed above, thus preventing any movement between the successivespinous processes and aiding in fusion between the two. If some movementis desired, then the arms are not locked against one another and theimplant 3 allows for some dynamic movement between the spinousprocesses.

FIG. 4 is an exploded perspective view of another embodiment of aninterspinous fusion implant (“ISP”) 30. Like implant 2, ISP 30 isnon-dynamic. It is made of two interconnecting components, a firstimplant component 80 and a second implant component 81. Each of implantcomponents 80 and 81 include subcomponents that will be describedfurther.

Implant component 80 includes a lateral bone spacer 80 a. Lateral bonespacer 80 a has a center ring 80 b. Center ring 80 b forms a roundopening 80 c through which various substances, such as bone grafts ornatural or synthetic bone growth stimulating substances, such assynthetic or natural bone matrix, may be passed through opening 80 c.Extending laterally in one direction from center ring 80 b is superiorbone anchor housing 82.

Extending laterally in the exact opposite direction from center ring 80b is inferior bone anchor housing 82 a. Both superior and inferior boneanchor housings 82 and 82 a can be circular in shape for optimumanchoring capacity to the spinous process. In one embodiment, thesuperior and inferior bone anchor housings 82 and 82 a are the sameshape and size. In other embodiments, they are different shapes and/orsizes. In one embodiment, a straight line runs through the center ofeach of housings 82, 82 a and center ring 80 b, i.e., they are at anangle of 180° from one another as shown in FIG. 4. The distance betweenthe ends of superior and inferior bone anchor housings 82 and 82 a canbe between about 30 mm and about 50 mm. In one embodiment, it is betweenabout 35 mm and about 40 mm. In other embodiments, it is about 30 mm, 35mm, 40 mm, 45 mm or 50 mm.

Within each of bone anchor housings 82 and 82 a are self-aligning boneanchor assemblies 83 and 83 a respectively. Each of bone anchoringassemblies 83 and 83 a contain one or more (four as shown in FIG. 4)spikes 84 and 84 a respectively that can penetrate bone. Spikes 84 and84 a protrude transversely in an inward direction from bone anchoringassemblies 83 and 83 a. Spikes 84 and 84 a are designed to penetrate thebone of the spinous process. While spikes 84 penetrate one spinousprocess, spikes 84 a penetrate the next spinous process inferior to theone being penetrated by spikes 84. In addition, superior and inferioranchor housings 82 and 82 a may be made of a unibody construction withcenter ring 80 b, or alternatively, they may be secured to armsprojecting from center ring 80 b by pins or other means that permitsuperior and inferior anchor housings 82 and 82 a to freely pivot at anangle relative to center ring 80 b.

Projecting transversely from the inner side of lateral bone spacer 80 aand at a substantially 90° angle from lateral bone spacer 80 a are twoopposing zip lock flanges 87 and 87 a, and two opposing bone abutments86 and 86 a. Alternatively, flanges 87 and 87 a can be slightly biasedinward toward each other for the purpose of forming a tight grip onbarrel 97. A longitudinal axis extends from the center of center ring 80b to the distal ends of zip lock flanges 87 and 87 a and bone abutments86 and 86 a. Zip lock flanges 87 and 87 a are slightly curved alongtheir width forming the same arc as the circular center ring 80 b fromwhich they extend transversely. Zip lock flanges 87 and 87 a areopposite each other and face each other as shown in FIG. 4. At thedistal end of each of zip lock flanges 87 and 87 a are one or more ziplock locking teeth 91 and 91 a respectively that protrude from theinward facing surfaces of zip lock flanges 87 and 87 a respectively.FIG. 4 shows that flanges 87 and 87 a have five zip lock teeth, but itcan be fewer or more than that number of teeth, such as 6, 7, 8, 9, 10or more teeth. Each of zip lock teeth 91 and 91 a form a top angledsliding face and a back locking ridge as shown in FIG. 4. The slidingface is angled to allow the teeth to slide forward and mate with the ziplock recesses or holes in the second implant component 81. The backlocking ridge of teeth 91 and 91 a can form a substantially 90° anglewith the zip lock flanges 87 and 87 a or they can be angled toward thecenter ring 80 b thus forming an acute angle between the back lockingridge and zip lock flanges 87 and 87 a. If the angle is acute, thenteeth 91 and 91 a will be taller (i.e., they will extend further fromtheir respective zip lock flange 87 and 87 a) than when the angle is asubstantially 90° angle for reasons that will be explained furtherbelow. The longer teeth will protrude through recesses 90 and 90 a at anangle thus creating a force that pulls second implant component 81toward zip lock flanges 87 and 87 a and prevents splaying of flanges 87and 87 a away from implant component 81. However, when the angle issubstantially 90° and the walls forming the holes or recesses 90 and 90a are at 90°, then there is greater surface area contact between theback ridge of teeth 91 and 91 a and the walls of recesses 90 and 90 a,which increases the forces between teeth 91 and 91 a and theirrespectively mated recesses 90 and 90 a. The 90° configuration alsoreduces the risk of teeth breaking since the pressure on the back ridgeis spread out across the entire surface area of the ridge rather than onjust the narrow strip that makes contact with the edges of recesses 90and 90 a. Teeth 91 and 91 a lock first and second components 80 and 81longitudinally, radially, and transversely with respect to one anotherdue to the forces between teeth 91 and 91 a and recesses 90 and 90 ainto which they slide. The outward facing surfaces of zip lockingflanges 87 and 87 a are substantially smooth.

Bone abutments 86 and 86 a face each other and extend transversely fromcenter ring 80 b. As shown in FIG. 4, they are both slightly roundedalong their width thus forming the same arc as circular center ring 80 bfrom which they extend transversely. Each of bone abutments 86 and 86 ahas a fusion window 85 and 85 a respectively. Fusion windows 85 and 85 aallow fusion between adjacent spinous processes through the barrelformed by the connection between the first and second implant components80 and 81. The outer facing surface of bone abutments 86 and 86 a may besmooth. Alternatively, they may be roughened to form more frictionbetween bone abutments 86 and 86 a and the spinous processes which theyrespectively abut. Increased friction will minimize any movement betweenthe spinous processes and ISP 30 once ISP 30 is implanted betweenadjacent spinous processes.

Second implant component 81 mates with first implant component 80.Second implant component 81 has a lateral bone anchor 81 a that facesand mirrors lateral bone spacer 80 a. Lateral bone anchor 81 a has amain function that is different than that of lateral bone spacer 80 a.Whereas lateral bone spacer 80 has abutments 86 and 86 a extendingtransversely to abut adjacent spinous processes and to keep the adjacentspinous processes separated from one another at a predetermined distancecorresponding with the distance between the two bone abutments 86 and 86a, the primary purpose of lateral bone anchor 81 is not to haveabutments extending from it, but to instead have a connecting barrel 97extending transversely from it, which allows lateral bone spacer 80 aand lateral bone anchor 81 a to move toward or away from one another andto form a lock once the proper distance for anchoring to the spinousprocesses is determined.

Like lateral bone spacer 80 a, lateral bone anchor 81 a has a centerring 81 b. Center ring 81 b forms a round opening 81 c through whichvarious substances, such as natural or synthetic bone grafts or bonegrowth stimulating substances such as natural or synthetic bone matrix,may be passed through center ring 81 b. Extending laterally in onedirection from center ring 81 b is superior bone anchor housing 82 c.Extending laterally in the exact opposite direction from center ring 81b is inferior bone anchor housing 82 d. Both superior and inferior boneanchor housings 82 c and 82 d can be circular in shape for optimumanchoring capacity to the spinous process. In one embodiment, superiorand inferior bone anchor housings 82 c and 82 d are the same shape andsize. In other embodiments, they are different shapes and/or sizes. Inone embodiment, a straight line runs through the center of each ofhousings 82 c, 82 d and center ring 81 b, i.e., they are at an angle of180° from one another as shown in FIG. 4. The distance between the endsof superior and inferior bone anchor housings 82 c and 82 d can bebetween about 30 mm and about 50 mm. In one embodiment, it is betweenabout 35 mm and about 40 mm. In other embodiments, it is about 30 mm, 35mm, 40 mm, 45 mm or 50 mm. In any case, the distance between the ends ofbone anchor housings 82 c and 82 d will be the same as the distancebetween the ends of bone anchor housings 82 and 82 a.

Within each of housings 82 c and 82 d are self-aligning bone anchorassemblies (reference numbers not shown). Each of said bone anchoringassemblies contain one or more (four in one embodiment) spikes that canpenetrate bone. The spikes are the same as spikes 84 and 84 a, and theyprotrude transversely from the inner side of bone anchoring assemblies82 c and 82 d. The spikes are designed to penetrate the bone of thespinous process. While spikes extending from bone anchor housing 82 cpenetrate one spinous process, spikes extending from bone anchor housing82 d penetrate the next spinous process inferior to the one beingpenetrated by spikes extending from bone anchor housing 82 c. Inaddition, superior and inferior anchor housings 82 c and 82 d may bemade of a unibody construction with center ring 81 b, or alternatively,they may be secured to arms projecting from center ring 81 b by pins orother means that permit superior and inferior anchor housings 82 c and82 d to freely pivot at an angle relative to center ring 81 b. The outersides of bone anchoring assemblies 82, 82 a, 82 c and 82 d haveindentations 88 that receive a compression tool that is used to forcethe components 80 and 81 toward each other and form a zip-lockedengagement as the compression tool forces flanges 87 and 87 a to slideover barrel 97.

Center ring 81 b has holes 89 and 89 a that are arcuate and are shapedand sized to receive the distal ends of the bone abutments 86 and 86 arespectively. Holes 89 and 89 a are opposite each other on the centerring 81 b. When the bone abutments 86 and 86 a mate respectively withholes 89 and 89 a, first and second components 80 and 81 are preventedfrom spinning relative to one another, and they become locked radiallyin place with respect to one another (see FIG. 5). Center ring 81 b alsohas holes 89 c and 89 d that are arcuate and are shaped and sized toreceive the distal ends of zip lock flanges 87 and 87 a respectively(see FIG. 5).

Projecting transversely from the inner side of lateral bone anchor 81 aand at a substantially 90° angle from lateral bone anchor 81 a is abarrel 97. Barrel 97 can have a diameter of between about 5.0 mm andabout 25 mm. In various embodiments, it has a diameter of about 5.0 mm,6.0 mm, 7.0 mm, 8.0 mm, 9.0 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15mm, 16 mm, 17 mm, 18 mm, 19 mm, 20 mm, 21 mm, 22 mm, 23 mm, 24 mm or 25mm. The length of barrel 97 can be between about 15 mm and about 30 mm.In various embodiments, it has a length of about 15 mm, 16 mm, 17 mm, 18mm, 19 mm, 20 mm, 21 mm, 22 mm, 23 mm, 24 mm, 25 mm, 26 mm, 27 mm, 28mm, 29 mm or 30 mm. Barrel 97 contains two columns of zip lock recesses90 and 90 a. Zip lock recesses 90 are opposite zip lock recesses 90 a onthe barrel 97. The column of zip lock recesses 90 is aligned with hole89 c, and the column of zip lock recesses 90 a is aligned with hole 89d. Zip lock recesses 90 receive and mate with teeth 91 of zip lockflange 87, and zip lock recesses 90 a receive and mate with teeth 91 aof zip lock flange 87 a. In on embodiment, as shown in FIG. 4, zip lockrecesses 90 and 90 a are elongated holes or slits that are shaped toreceive teeth 91 and 91 a respectively. In another embodiment (not shownin the figures) zip lock recesses 90 and 90 a are formed by protrudingteeth that extend radially outward from the barrel 97. Such teeth can beangled or sloped in the opposite direction of teeth 91 and 91 a so thatteeth 91 and 91 a will slide over teeth 90 and 90 a respectively whencomponents 80 and 81 are forced into engagement with each other. Whenteeth 91 and 91 a engage with teeth 90 and 90 a respectively component80 cannot be pulled apart from component 81, because the vertical backside of teeth 91 and 91 a will catch against the vertical front side ofteeth 90 and 90 a respectively. In yet another embodiment, zip-lockrecesses are formed by straight vertical protuberances over which teeth91 and 91 a slide. When teeth 91 and 91 a engage with teethprotuberances 90 and 90 a respectively component 80 cannot be pulledapart from component 81, because the vertical back side of teeth 91 and91 a will catch against the vertical protuberances 90 and 90 arespectively. Barrel 97 also has windows 97 a and 97 b that are oppositeone another on barrel 97. Windows 97 a and 97 b are the same size andshape as windows 85 and 85 a and align with windows 85 and 85 arespectively when components 80 and 81 are mated to one another.

First and second components 80 and 81 mate with one another in thefollowing manner. As the two are brought toward one another, zip lockflanges 87 and 87 a glide over the columns of zip lock recesses 90 and90 a respectively of barrel 97. As flanges 87 and 87 a glide over barrel97, bone abutments 86 and 86 a glide over barrel 97 as well, and windows85 and 85 a become aligned respectively with windows 97 a and 97 b ofbarrel 97. Barrel 97 thus becomes nested within bone abutments 86 and 86a and flanges 87 and 87 a of first component 80, such that barrel 97becomes radially nested within first component 80 (see FIG. 5). Oncewindows 85 and 85 a are aligned with windows 97 a and 97 b respectively,a barrel is formed by the mating of component 80 and 81 with opposingwindows (85 and 97 a form one window while 85 a and 97 b form another)through which bone can grow, such that bone from one spinous process caneventually fuse with bone from the adjacent spinous process through thewindows. In addition, bone growth stimulating materials, such as naturalor synthetic bone matrix or bone graft material, can be inserted througheither of openings 80 c or 81 c into the barrel to help stimulate thegrowth of bone between the adjacent spinous processes.

When first and second components 80 and 81 are locked with one anotherthrough the mating of teeth 91 and 91 a with zip lock recesses 90 and 90a respectively, anchor housings 82 and 82 c are aligned opposite withone another along a single longitudinal axis, and anchor housings 82 aand 82 d are aligned opposite with one another along a singlelongitudinal axis (see FIG. 5).

When components 80 and 81 are mated as described above, they cannot bedisengaged from one another without the use of a splaying tool thatsplays the zip-lock flanges 87 and 87 a away from barrel 97. Thus, thetwo components 80 and 81 are reversibly locked together, but they cannotbe disengaged or unlocked from one another except with the use of asplaying tool. Thus, component 81 can slide into component 80 and becomereversibly locked to component 80 without any additional tools, but thetwo components cannot be separated from one another once they areengaged without a release tool that splays zip-lock flanges 87 and 87 aradially apart from barrel 97. This results in ISP 30 being a devicethat can be locked to the spinous processes without a set screw or screwdrivers or the need for any additional locking tools that requireadjustment of screws. Components 80 and 81 need only be pushed or forcedtogether and they will form a tight lock to one another that is notprone to failure and is only reversible with a splaying tool. This is asignificant improvement over older implants that require additionaltooling to be secured in place between spinous processes. The columns ofmultiple or a series of teeth 91 and 91 a mating with multiple or aseries of recesses 90 and 90 a respectively prohibits the migration ofcomponent 81 away from component 80 once the two components are engagedto one another through the described zip-locking mechanism, and thisminimizes the risk of long-term mechanical failure of ISP 30 once it hasbeen implanted. These same features, benefits, and improvements are alsoequally applicable to ISP 200, ISP 285, and ISP 300 described laterherein, because they both have the same zip-lock mechanism as ISP 30.

First and second components 80 and 81 mate with one another to form asingle ISP unit that not only separates two adjacent spinous processesfrom one another at a predetermined distance, but keeps them locked withrespect to one another as a result of the penetration of the spinousprocesses by the anchoring spikes (described above). The bone abutments86 and 86 a thus prevent extension between adjacent spinous processes,while the anchors prevent flexion between two adjacent spinous processes(see FIG. 6).

In one method of implantation, the assembled ISP 30 can be insertedbetween two spinous processes of adjacent vertebrae in an anterior toposterior direction after severing spinous ligaments to remove them fromthe path of implantation. In another method of implantation, no spinousligaments are severed and the first and second components 80 and 81 areseparated and can each individually be inserted from opposing lateraldirections toward each other anterior to the undisturbed spinousligaments. In any case, the ISP 30 is inserted between two spinousprocesses of adjacent vertebrae, and multiple ISP units can be stackedone after another (see FIG. 6). First and second components 80 and 81are squeezed or pushed toward one another until the spikes on opposinganchor housings 82 and 82 c penetrate the outer sides of the superiorspinous process while the spikes on anchoring housings 82 a and 82 dpenetrate the outer sides of the adjacent and inferior spinous process.With the penetration of the spikes the ISP 30 prohibits both extension(as a result of bone abutments 86 and 86 a abutting the inner spinousprocess) and flexion (as a result of the anchoring by the spikes).

The locking mechanism described with respect to FIG. 4 is the mating ofa series of successive teeth 91 and 91 a with a series of successiverecesses 90 and 90 a respectively. This locking mechanism poses asignificant advantage over previous locking mechanisms that use setscrews, nuts or bolts. The use of a series of successive teeth (i.e.,two or more teeth, e.g., two, three, four, five, six, seven, eight,nine, ten or more teeth) creates forces that are significantly greaterthan can be achieved using a set screw, nut or bolt. Moreover set screwscan loosen and come undone with time allowing the two parts of a spinalimplant to slide apart from each other. The use of a series ofsuccessive zip locking teeth, such as in FIG. 4, prevents this problem.Moreover, disengagement of the described first and second components 80and 81 from one another requires a two-step process: pulling the flanges87 and 87 a apart from one another (a radial spreading force) whilesimultaneously pulling components 80 and 81 longitudinally away from oneanother (a longitudinal pushing or pulling force). The likelihood ofboth forces occurring at the same time inadvertently or through failureof the device over time are much lower than devices that use set screws,where the screw can become undone over time and then subsequent movementof the two parts away from each other can happen at a later time thuscausing a failure of the device in situ. This type of locking mechanismis also a significant improvement over a simple ratchet, because aratchet does not create the firm grip and increased forces created bythe engagement of a series of successive teeth with a series ofsuccessive recesses.

ISP 30 can be packaged as part of a kit that comes with an implantationtool that controls the insertion of ISP 30 between spinous processes anda removal tool that is designed to splay the flanges 87 and 87 a awayfrom barrel 97 so that the two components 80 and 81 can be separatedfrom one another. The implantation tool can be a compression tool thatengages the indentations 88 on the opposing arms 82 and 82 a on the onehand and 82 c and 82 d on the other hand, and squeezes the twocomponents 80 and 81 together forcing the flanges 87 and 87 a to advanceforward over the zip-lock recess columns 90 and 90 a respectively andtoward and through openings 89 c and 89 d respectively. The kit can alsoinclude synthetic or natural bone matrix that can be used with ISP 30 topromote fusion between successive vertebrae. The bone matrix can bepacked in the barrel 97 promoting bone growth between a superiorvertebra and an inferior vertebra through windows 85, 85 a, 97 a, and 97b. ISP connecting rods and couplers 500 can also be included in the kit.ISP 200, 285 and 300 can also be packaged as part of a kit with the sametools and materials described here with respect to ISP 30. Such kits canalso come with instructions for use. The instructions for use caninclude the following steps, which can be part of a method of implantingISP 30 (also ISP 200, 285 and 300):

-   -   i. Remove ISP 30 (or 200, 285 or 300) from packaging    -   ii. Manually align the zip-lock flanges with zip-lock recess        columns respectively.    -   iii. Manually guide zip-lock flanges over zip-lock recess        columns of the barrel until at least one of the teeth of each of        the zip-lock flanges respectively engages at least one of the        recesses of the zip-lock recess columns respectively.    -   iv. Pack the barrel (this refers to barrel 97) with bone growth        matrix (this step can be performed after ISP is implanted as        well).    -   v. Implant the assembled ISP 30 (or 200, 285 or 300) by guiding        the zip-locked section between adjacent spinous processes while        the arms of the one component are aligned with the outer sides        of the two adjacent spinous processes and the other arms of the        other component are aligned with the opposite outer sides of the        same two adjacent spinous processes.    -   vi. Adjust the angle of the ISP 30 (or 200, 285 or 300) so that        it is implanted in the orientation desired. The following        orientations are suggested:        -   1. The superior end of ISP is anterior to the inferior end            of ISP, such that the superior end of ISP is adjacent the            lamina of the superior spinous process while the inferior            end of ISP is adjacent the posterior end of the inferior            spinous process (see FIG. 6 as an example of this).        -   2. The superior end of ISP is posterior to the inferior end            of ISP, such that the superior end of ISP is adjacent the            posterior end of the superior spinous process while the            inferior end of ISP is adjacent the lamina of the inferior            spinous process (this is the opposite of the configuration            depicted in FIG. 6).    -   vii. Engage the implantation tool to the indentations on the        outer sides of the arms. Cause the implantation tool to squeeze        the two components toward each other forcing the flanges to        advance forward over the zip-lock recess columns and toward and        through openings at the opposite ends (180° apart) of the barrel        that receive the ends of the flanges.    -   viii. Cease causing the implantation tool to squeeze the two        components together once the spikes on the arms of the two        components have engaged the bone on opposite sides of the        adjacent spinous processes and have burrowed into the bone.    -   ix. Check to make sure that the ISP is firmly anchored to the        successive spinous processes.    -   x. Add additional ISPs to form a stack of successive ISPs        anchored to successive spinous processes in the same manner        described above.        -   1. If additional ISPs are implanted, they may be anchored            together using the rods provided here connected to the outer            sides of the arms using couplers (this feature is described            in more detail below).    -   xi. To remove an ISP 30 (or 200, 285 or 300) use the removal        tool to splay flanges on the one component away from the barrel        of the other component thus disengaging teeth on the flanges        from the recesses on the barrel, and pull the two components        away from each other until they are disengaged from one another.

In another example, FIG. 7 depicts ISP 285, which is similar to ISP 30,except that it is designed to be used in the sacral region 290 of thevertebral column, between the last spinous process 289, which projectsposteriorly from the L5 vertebral body, and the sacrum. The componentsof ISP 285 are the same as those of ISP 30, except that the inferiorbone anchor housings 282 a and 282 d of ISP 285 are different frominferior bone housings 82 a and 82 d of ISP 30. Anchor housing 282 aforms a flared wing 284 a with a hole 287, and anchor housing 282 dforms a flared wing 284 d with a hole 286. Hole 287 and hole 286 eachreceives a set screw 288, that anchors the flared wings 284 a and 284 drespectively to the sacrum. Thus, the inferior bone anchor housings 282a and 282 d of ISP 285 are anchored to the sacrum using set screwsrather than spikes. In contrast, like ISP 30, superior bone housings 282c and 282 of ISP 285 use spikes 284 c and 284 b respectively to anchorthe superior housings 282 c and 282 to the spinous process of the L5vertebral body. ISP 285 can be seen in its implanted form in FIG. 7 toillustrate the written description set forth above.

Inferior housings 282 a and 282 d include sacral abutments 283 a and 283d from which the flared wings 284 a and 284 d project laterallyoutwardly. Abutments 283 a and 283 d face each other when ISP is in itsassembled state. Abutments 283 a and 283 d can be parallel to oneanother in one embodiment. In another embodiment, abutments 283 a and283 d are not parallel with one another, and instead they each form aslope that matches the contour of the sacrum, such that the top edges ofeach of abutments 283 a and 283 d are nearer one another than theirbottom edges. Relative to a plane that runs perpendicular to barrel 297and parallel with rings 280 a and 281 a, abutments 283 a and 283 d couldform an angle of between about 0 degrees and about 45 degrees, i.e.,that angle can be about 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13,14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31,32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, or 45 degrees.Flared wings 284 a and 284 d project outwardly from the inferiorhousings 282 a and 282 d. Relative to a plane that runs perpendicular tobarrel 297 and parallel with rings 280 a and 281 a, flared wings 284 aand 284 d could form an angle of between about 90 degrees and about 150degrees, i.e., that angle can be about 90, 91, 92, 93, 94, 95, 96, 97,98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112,113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126,127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140,141, 142, 143, 144, 145, 146, 147, 148, 149, or 150 degrees.

In another example, FIG. 11 is an exploded perspective view of anotherembodiment of an interspinous fusion implant (“ISP”) 200. A firstcomponent 180 and second component 181 are fitted together and locktogether to form ISP 200 in the same manner as ISP 30 of FIG. 4. ISP 200is similar to ISP 30 but with a few exceptions, which will be describedhere. Like first component 80 of ISP 30, first component 180 of ISP 200,includes a lateral bone spacer 180 a. Lateral bone spacer 180 a has acenter ring 180 b. Center ring 180 b forms a round opening 180 c throughwhich various substances, such as bone grafts or bone growth stimulatingsubstances, may be passed through center ring 180 b. Extending laterallyin one direction from center ring 180 b is superior bone anchor housing182. Extending laterally in the exact opposite direction from centerring 180 b is inferior bone anchor housing 182 a. Both superior andinferior bone anchor housings 182 and 182 a can be circular in shape foroptimum anchoring capacity to the spinous process. In one embodiment,the superior and inferior bone anchor housings 182 and 182 a are thesame shape and size. In other embodiments, they are different shapesand/or sizes. In one embodiment, a straight line runs through the centerof each of housings 182, 182 a and center ring 180 b, i.e., they are atan angle of 180° from one another as shown in FIG. 11.

Within each of housings 182 and 182 a are self-aligning bone anchorassemblies 183 and 183 a. Each of bone anchoring assemblies 183 and 183a contain one or more (four as shown in FIG. 11) spikes 184 and 184 athat can penetrate bone. Spikes 184 and 184 a protrude transversely inan inward direction from bone anchoring assemblies 183 and 183 a. Spikes184 and 184 a are designed to penetrate the bone of the spinous process.While spikes 184 penetrate one spinous process, spikes 184 a penetratethe next spinous process inferior to the one being penetrated by spikes184. In addition, superior and inferior anchor housings 182 and 182 amay be made of a unibody construction with center ring 180 b, oralternatively, they may be secured to arms projecting from center ring180 b by pins or other means that permit superior and inferior anchorhousings 182 and 182 a to freely pivot at an angle relative to centerring 180 b. Bone anchoring assemblies 183 and 183 a are held withintheir respective housings 182 and 182 a respectively by pins 193 and 193a. Pins 193 and 193 a allow bone anchoring assemblies 183 and 183 a topivot within their respective housings 182 and 182 a around an axis ofrotation formed by pins 193 and 193 a. Thus, bone anchoring assemblies183 and 183 a can pivot at an angle relative to housings 182 and 182 arespectively as shown in FIG. 11. The maximum pivot angle is determinedby the size of assemblies 183 and 183 a relative to housings 182 and 182a. The greater the distance between the outer wall of assemblies 183 and183 a and the inner wall of their respective housings 182 and 182 a, thegreater the maximum pivot angle will be. The maximum pivot angle canbe + or −1°, 2°, 3°, 4°, 5°, 6°, 7°, 8°, 9°, 10°, 11°, 12°, 13°, 14°,15°, 16°, 17°, 18°, 19°, 20°, 21°, 22°, 23°, 24°, 25°, 26°, 27°, 28°,29°, 30°, 31°, 32°, 33°, 34°, 35°, 36°, 37°, 38°, 39°, 40°, 41°, 42°,43°, 44° or 45°. In one embodiment, the maximum pivot angle is + or −between about 1-10°. In another embodiment, the maximum pivot angle is +or − about 7°. As shown in FIG. 11, anchor assemblies 183 and 183 a haveaxes of rotation that are perpendicular to one another, such that theaxis of rotation of one of the assemblies is perpendicular to the axisof rotation of the other anchor assembly. In one embodiment, anchorassembly 183 pivots about a horizontal axis of rotation as shown in FIG.11, while anchor assembly 183 a pivots about a vertical axis of rotationas shown in FIG. 11. In another embodiment, anchor assembly 183 pivotsabout a vertical axis of rotation, while anchor assembly 183 a pivotsabout a horizontal axis of rotation. However, pins 193 and 193 a do nothave to be aligned perpendicular to one another and they do not have tobe horizontal and vertical. The pins can be aligned along the diameterof their respective anchor housings at any angle so long as the anchorassemblies 183 and 183 a are able to pivot about the axis of rotationformed by the pins.

As with lateral spacer 80 a of ISP 30, projecting transversely from thelateral bone spacer 180 a and at a substantially 90° angle from lateralbone spacer 180 a are two opposing zip lock flanges 187 and 187 a, andtwo opposing bone abutments 186 and 86 a. Alternatively, flanges 187 and187 a can be slightly biased inward toward each other for the purpose offorming a tight grip on barrel 197. A longitudinal axis extends from thecenter of center ring 180 b to the distal ends of zip lock flanges 187and 187 a and bone abutments 186 and 186 a. Zip lock flanges 187 and 187a are slightly rounded along their width forming the same arc as thecircular center ring 180 b from which they extend transversely. Zip lockflanges 187 and 187 a are opposite each other and face each other asshown in FIG. 11. At the distal end of each of zip lock flanges 187 and187 a are one or more zip lock locking teeth 191 and 191 a that protrudefrom the inward facing surfaces of the zip lock flanges 187 and 187 a.FIG. 11 shows that flanges 187 and 187 a have five zip lock teeth, butit can be fewer or more than that number of teeth. Each of zip lockteeth 191 and 191 a form a top angled sliding face and a back lockingridge as shown in FIG. 11. The sliding face is angled to allow the teethto slide forward and mate with the zip lock recesses or holes in secondimplant component 181. The back locking ridge of teeth 191 and 191 a canform a substantially 90° angle with the zip lock flanges 187 and 187 aor they can be angled toward the center ring 180 b thus forming an acuteangle between the back locking ridge and zip lock flanges 187 and 187 a.If the angle is acute, then teeth 191 and 191 a will be taller (i.e.,they will extend further from their respective zip lock flange 187 and187 a) than when the angle is a substantially 90° angle for reasons thatwill be explained further below. The longer teeth will protrude throughthe recesses 190 and 190 a at an angle thus creating a force that pullssecond implant component 181 toward zip lock flanges 187 and 187 a andprevents splaying the flanges 187 and 187 a away from implant component181. However, when the angle is substantially 90° and the walls formingthe holes or recesses 190 and 190 a are at 90°, then there is greatersurface area contact between the back ridge of teeth 191 and 191 a andthe walls of recesses 190 and 190 a, which increases the forces betweenteeth 191 and 191 a and their respectively mated recesses 190 and 190 a.The 90° configuration also reduces the risk of teeth breaking since thepressure on the back ridge is spread out across the entire surface areaof the ridge rather than on just the narrow strip that makes contactwith the edges of recesses 190 and 190 a. Teeth 191 and 191 a lock firstand second components 180 and 181 longitudinally, radially, andtransversely with respect to one another due to the forces between teeth191 and 191 a and recesses or holes 190 and 190 a into which they slide.The outward facing surfaces of zip locking flanges 187 and 187 a aresubstantially smooth. At the distal end of the top surface of each ofzip lock flanges 187 and 187 a are release nubs 194 and 194 arespectively, which contain holes 195 and 195 a respectively. A releasetool can be inserted into each of holes 195 and 195 a to bend flanges187 and 187 a away from barrel 197, thus pulling teeth 191 and 191 a outof recesses 190 and 190 a respectively. In on embodiment, as shown inFIG. 11, zip lock recesses 190 and 190 a are elongated holes or slitsthat are shaped to receive teeth 191 and 191 a respectively. In anotherembodiment (not shown in the figures) zip lock recesses 190 and 190 aare formed by protruding teeth that extend radially outward from thebarrel 197. Such teeth can be angled or sloped in the opposite directionof teeth 191 and 191 a so that teeth 191 and 191 a will slide over teeth190 and 190 a respectively when components 180 and 181 are forced intoengagement with each other. When teeth 191 and 191 a engage with teeth190 and 190 a respectively component 180 cannot be pulled apart fromcomponent 181, because the vertical back side of teeth 191 and 191 awill catch against the vertical front side of teeth 190 and 190 arespectively. In yet another embodiment, zip-lock recesses are formed bystraight vertical protuberances over which teeth 191 and 191 a slide.When teeth 191 and 191 a engage with teeth protuberances 190 and 190 arespectively component 180 cannot be pulled apart from component 181,because the vertical back side of teeth 191 and 191 a will catch againstthe vertical protuberances 190 and 190 a respectively.

Bone abutments 186 and 186 a face each other and extend transverselyfrom the inner side of lateral bone spacer 180 a. As shown in FIG. 11,they are both slightly rounded along their width forming the same arc asthe circular center ring 180 b from which they extend transversely. Eachof bone abutments 186 and 186 a has a fusion window 185 and 185 arespectively. Fusion windows 185 and 185 a allow fusion between adjacentspinous processes through the barrel formed by the connection or matingbetween the first and second implant components 180 and 181. The outerfacing surface of the bone abutments 186 and 186 a may be smooth.Alternatively, they may be roughened to form more friction between boneabutments 186 and 186 a and the spinous processes which theyrespectively abut. Increased friction will minimize any movement betweenthe spinous processes and ISP 200 once ISP 200 is implanted betweenadjacent spinous processes.

Second implant component 181 mates with first implant component 180.Second implant component 181 has a lateral bone anchor 181 a that facesand mirrors lateral bone spacer 180 a. Lateral bone anchor 181 a has amain function that is different than that of lateral bone spacer 180 a.Whereas lateral bone spacer 180 has abutments 186 and 186 a extendinglongitudinally to abut adjacent spinous processes and to keep theadjacent spinous processes separated from one another at a predetermineddistance corresponding with the distance between the two bone abutments186 and 186 a, the primary purpose of lateral bone anchor 181 is not tohave abutments extending from it, but to instead have a connectingbarrel 197 extending transversely from it, which allows lateral bonespacer 180 a and lateral bone anchor 181 a to move toward or away fromone another and to form a lock once the proper distance for anchoring tothe spinous processes is determined.

Like lateral bone spacer 180 a, lateral bone anchor 181 a has a centerring 181 b. Center ring 181 b forms a round opening 181 c through whichvarious substances, such as bone grafts or bone growth stimulatingsubstances, may be passed through center ring 181 b. Extending laterallyin one direction from center ring 181 b is superior bone anchor housing182 c. Extending laterally in the exact opposite direction from centerring 181 b is inferior bone anchor housing 182 d. Both superior andinferior bone anchor housings 182 c and 182 d can be circular in shapefor optimum anchoring capacity to the spinous process. In oneembodiment, superior and inferior bone anchor housings 182 c and 182 dare the same shape and size. In other embodiments, they are differentshapes and/or sizes. In one embodiment, a straight line runs through thecenter of each of housings 182 c, 182 d and center ring 181 b, i.e.,they are at an angle of 180° from one another as shown in FIG. 11.

Within each of housings 182 c and 182 d are self-aligning bone anchorassemblies 183 c and 183 d. Each of said bone anchoring assemblies 183 cand 183 d contain one or more (four in one embodiment) spikes that canpenetrate bone. The spikes are the same as spikes 184 and 184 a, andthey protrude transversely from the inner side of bone anchoringassemblies 182 c and 182 d. The spikes are designed to penetrate thebone of the spinous process. While spikes extending from bone anchorhousing 182 c penetrate one spinous process, spikes extending from boneanchor housing 182 d penetrate the next spinous process inferior to theone being penetrated by spikes extending from bone anchor housing 182 c.In addition, superior and inferior anchor housings 182 c and 182 d maybe made of a unibody construction with center ring 181 b, oralternatively, they may be secured to arms projecting from center ring181 b by pins or other means that permit superior and inferior anchorhousings 182 c and 182 d to freely pivot at an angle relative to centerring 181 b. Bone anchoring assemblies 183 c and 183 d are held withintheir respective housings 182 c and 182 d respectively by pins 192 and192 a. Pins 192 and 192 a allow bone anchoring assemblies 183 c and 183d to pivot within their respective housings 182 c and 182 d around anaxis of rotation formed by pins 192 and 192 a. The bone anchoringassemblies can pivot at an angle relative to housings 182 c and 182 drespectively as shown in FIG. 11. The maximum pivot angle is determinedby the size of assemblies 183 c and 183 d relative to housings 182 c and182 d. The greater the distance between the outer wall of assemblies 183c and 183 d and the inner wall of their respective housings 182 c and182 d, the greater the maximum pivot angle will be. The maximum pivotangle can be + or −1°, 2°, 3°, 4°, 5°, 6°, 7°, 8°, 9°, 10°, 11°, 12°,13°, 14°, 15°, 16°, 17°, 18°, 19°, 20°, 21°, 22°, 23°, 24°, 25°, 26°,27°, 28°, 29°, 29°, 30°, 31°, 32°, 33°, 34°, 35°, 36°, 37°, 38°, 39°,40°, 41°, 42°, 43°, 44° or 45°. In one embodiment, the maximum pivotangle is + or − between about 1-10°. In another embodiment, the maximumpivot angle is + or − about 7°. As shown in FIG. 11, anchor assembly 183c and 183 d have axes of rotation that are perpendicular to one another,such that the axis of rotation of one of the assemblies is perpendicularto the axis of rotation of the other anchor assembly. In one embodiment,anchor assembly 183 c pivots about a horizontal axis of rotation asshown in FIG. 11, while anchor assembly 183 d pivots about a verticalaxis of rotation as shown in FIG. 11. In another embodiment, anchorassembly 183 c pivots about a vertical axis of rotation, while anchorassembly 183 d pivots about a horizontal axis of rotation. However, pins192 and 192 a do not have to be aligned perpendicular to one another andthey do not have to be horizontal and vertical. The pins can be alignedalong the diameter of their respective anchor housings at any angle solong as the anchor assemblies 183 c and 183 d are able to pivot aboutthe axis of rotation formed by the pins. Laterally on each side of theouter side of each of center rings 180 b and 181 b are indentations 188(not visible on implant component 180), which receive a compression toolthat is used to manipulate the ISP 200 during surgical procedures.

Center ring 181 b has holes 189 a and 189 b that are arcuate and areshaped and sized to receive the distal ends of bone abutments 186 a and186 respectively. Holes 189 a and 189 b are opposite each other on thecenter ring 181 b. When bone abutments 186 a and 186 mate with holes 189a and 189 b respectively, first and second components 180 and 181 areprevented from spinning relative to one another, and they become lockedradially in place with respect to one another. Center ring 181 b alsohas apertures 189 c and 189 d that form open rings that are each open atthe top and are shaped and sized to receive the distal ends of zip lockflanges 187 and 187 a respectively. The open ring configuration allowsrelease nubs 194 and 194 a to slide into the apertures 189 c and 189 d.Release nubs 194 and 194 a are shaped to mate with apertures 189 c and189 d.

Projecting transversely from the inner side of lateral bone anchor 181 aand at a substantially 90° angle from lateral bone anchor 181 a isbarrel 197. Barrel 197 contains two columns of zip lock recesses 190 and190 a. Zip lock recesses 190 are opposite zip lock recesses 190 a on thebarrel 197. The column of zip lock recesses 190 is aligned with aperture189 c, and the column of zip lock recesses 190 a is aligned withaperture 189 d. Zip lock recesses 190 receive and mate with teeth 191 ofzip lock flange 187, and zip lock recesses 190 a receive and mate withteeth 191 a of zip lock flange 187 a. Barrel 197 also has window 197 aand another window opposite it (not visible in FIG. 11). Window 197 aand its opposite window (not visible) are the same size and shape aswindows 185 and 185 a and align with windows 185 and 185 a respectivelywhen components 180 and 181 are mated to one another.

First and second components 180 and 181 mate with one another in thefollowing manner. As the two are brought toward one another, zip lockflanges 187 and 187 a glide over the columns of zip lock recesses 190and 190 a of barrel 197. As the flanges 187 and 187 a glide over barrel197, bone abutments 186 and 186 a glide over barrel 197 as well, andwindows 185 and 185 a become aligned respectively with window 197 a andits opposite window of barrel 197. Barrel 197 thus becomes nested withinbone abutments 186 and 186 a and flanges 187 and 187 a of firstcomponent 180, such that barrel 197 becomes radially nested within firstcomponent 180. Once windows 185 and 185 a are aligned with window 197 aand its opposite window respectively, a barrel is formed by the matingof component 180 and 181 with opposing windows (185 and 197 a form onewindow while 185 a and the window opposite 197 a form another) throughwhich bone can grow, such that bone from one spinous process caneventually fuse with bone from the adjacent spinous process through thewindows. In addition, bone growth stimulating materials, such as naturalor synthetic bone matrix or bone graft material, can be inserted througheither of openings 180 c or 181 c into the barrel to help stimulate thegrowth of bone between the adjacent spinous processes.

When first and second components 180 and 181 are locked with one anotherthrough the mating of zip lock teeth 191 and 191 a with zip lockrecesses 190 and 190 a respectively, anchor housings 182 and 182 c arealigned opposite one another along a single longitudinal axis, andanchor housings 182 a and 182 d are aligned opposite one another along asingle longitudinal axis.

First and second components 180 and 181 mate with one another to form asingle ISP unit 200 that not only separates two adjacent spinousprocesses from one another at a predetermined distance, but keeps themlocked with respect to one another as a result of the penetration of thespinous processes by the anchoring spikes (described above). Boneabutments 186 and 186 a thus prevent extension between adjacent spinousprocesses, while the anchors prevent flexion between two adjacentspinous processes.

In one method of implantation, the assembled ISP 200 can be insertedbetween two spinous processes of adjacent vertebrae in an anterior toposterior direction after severing spinous ligaments to remove them fromthe path of implantation. In another method of implantation, no spinousligaments are severed and the first and second components 180 and 181are separated and can each individually be inserted from opposinglateral directions toward each other anterior to the undisturbed spinousligaments. In any case, ISP 200 is inserted between two spinousprocesses of adjacent vertebrae. First and second components 180 and 181are squeezed or pushed toward one another until the spikes on opposinganchor housings 182 and 182 c penetrate the superior spinous processwhile the spikes on anchoring housings 182 a and 182 d penetrate thesides of the adjacent and inferior spinous process. With the penetrationof the spikes the ISP 200 prohibits both extension (as a result of boneabutments 186 and 186 a abutting the inner spinous process) and flexion(as a result of the anchoring by the spikes).

The locking mechanism described with respect to FIG. 11 is the mating ofa series of teeth 191 and 191 a with a series of recesses 190 and 190 arespectively. This locking mechanism poses a significant advantage overprevious locking mechanisms that use set screws, nuts or bolts. The useof a series of teeth creates forces that are significantly greater thancan be achieved using a set screw, nut or bolt. Moreover set screws cancome undone with time allowing the two parts of a spinal implant toslide apart from each other. The use of a series of zip locking teeth,such as in FIG. 11, prevents this problem. Moreover, disengagement ofthe described first and second components 180 and 181 from one anotherrequires a two-step process: pulling the flanges apart from one another(a radial spreading force) while simultaneously pulling components 180and 181 longitudinally away from one another (a longitudinal pulling orpushing force). The likelihood of both forces occurring at the same timeinadvertently or through failure of the device over time are much lowerthan devices that use set screws, where the screw can become undone overtime and then subsequent movement of the two parts away from each othercan happen at a later time thus causing a failure of the device in situ.This type of locking mechanism is also a significant improvement over asimple ratchet, because a ratchet does not create the firm grip andincreased forces created by the engagement of a series of successiveteeth with a series of successive recesses.

Another important aspect of the embodiment depicted in FIG. 11 anddescribed above is the ability of the anchor assemblies 183, 183 a, 183c and 183 d to pivot about an axis of rotation. This gives ISP 200 moreflexibility and adaptability than it would otherwise have. It allows theanchor assemblies to orient themselves in an optimal angle toward thebone of the spinous process. Thus, the anchoring point of the spinousprocess does not have to be perfectly parallel with lateral bone spacer180 a and lateral bone anchor 181 a in order for the spikes to form anoptimal engagement with the spinous process, because the anchoringassembly can pivot to form a substantially parallel alignment with thebone thus forming the optimal surface area contact between the bone andthe spikes.

FIGS. 12a-14f depict another embodiment of a non-dynamic interspinousfusion implant (“ISP”) 300. ISP 300 is similar to ISP 200. It has thesame zip-locking mechanism as ISP 200. The difference is that theinferior arms 382 a and 382 d do not have swiveling anchor assemblies.Instead they have spikes that project inwardly from sloped inward faces,while the superior arms do have the same swiveling anchoring assembliesas ISP 200. This different feature of ISP 300 makes it also particularlyadapted for use in the sacral region like ISP 285. As shown in FIGS.12a-12f , ISP 300 has superior arms 382 and 382 c that face each otherand have the same swiveling anchor assemblies as ISP 200. At theopposite, inferior end of ISP 300 are arms 382 a and 382 d that alsoface each other, but they do not have swiveling anchor assemblies.Instead, they have sloped faces and spikes extending transversely fromthe faces toward each other. Zip lock flanges 387 and 387 a engage withtwo rows of opposing zip-lock recesses on barrel 397. This is the sameas with zip-lock flanges 187 and 187 a engaging with zip-lock recesses190 and 190 a respectively of ISP 200.

Like ISP 200, ISP 300 has two components: a first component 380 and asecond component 381. First component 380 is shown in FIGS. 14a-14f . Ithas a lateral bone spacer 380 a. Projecting in a superior direction fromlateral bone spacer 380 a is bone anchor housing 382. Projecting in aninferior direction from lateral bone spacer 380 a is bone anchor housing382 a.

Each spinous process projects in a posterior direction from the lamina,such that the base of each spinous process is integral with the laminaand curves into the transverse process. The base of each spinous processis its thickest point and the spinous process tapers inward from thebase to a midpoint and becomes thicker again at its posterior end. Thebone anchor housings 382 a and 382 d are meant to be anchored to thebase of the spinous process at its juncture with the lamina where itcurves outward to form the transverse process, or with the sacrum whichis also similarly sloped. To form a tight and continuous engagement withthe base of the spinous process or the sacrum, the inward facing side ofbone anchor housings 382 a and 382 d form a sloped faces 383 a and 383 drespectively. The slope of faces 383 a and 383 d is angled to match theangle at the base of spinous process (or sacrum) so that faces 383 a and383 d are each in virtually continuous engagement with the bone at thebase of the spinous process when implanted. Relative to a plane thatruns perpendicular to barrel 397 and parallel with rings 380 a and 381a, abutments 383 a and 383 d could form an angle of between about 0degrees and about 45 degrees, i.e., that angle can be about 0, 1, 2, 3,4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22,23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,41, 42, 43, 44, or 45 degrees. Spikes 340 a and 340 d project inwardlyfrom the abutments 383 a and 383 d respectively. As shown best in FIG.13e , spikes 340 d are substantially parallel with longitudinal axis x′of barrel 397 and are substantially perpendicular with a plane that runsperpendicular to barrel 397 and parallel with ring 381 a. Likewise, asshown best in FIG. 14e , spikes 340 a are substantially parallel withlongitudinal axis x of flanges 387 and 387 a and are substantiallyperpendicular with a plane that runs perpendicular to longitudinal axisx and parallel with ring 380 a. As shown in FIGS. 13e and 14e , thelongitudinal axes of spikes 340 a and 340 d form an acute angle withabutments 383 a and 383 d respectively. The angle and direction of thespikes 340 a and 340 d is important, because it results in a more securetransaction between the spikes and the bone of the sacrum. Spikes 340 aproject transversely from face 383 a and they are perpendicular to thebone anchor housing 382 a while forming an acute angle with face 383 a.This configuration of a sloped face with perpendicular spikes provides asecure long-term engagement between the inferior end of the implant andthe spinous process.

Extending transversely from bone spacer 380 a are zip-lock flanges 387and 387 a and opposing bone abutments 386 and 386 a, all of whichproject transversely from bone spacer 380 a in the same direction.Zip-lock flanges 387 and 387 a have already been discussed above. Boneabutments 386 and 386 a are similar to bone abutments 186 and 186 a,except that rather than forming a single window within each of theabutments, each abutment has a pair of windows separated by a pillar.Bone abutment 386 has windows 385-1 and 385-2 separated by pillar 385-3.Bone abutment 386 a has windows 385 a-1 and 385 a-2 separated by pillar385 a-3. The windows allow for bone growth through the windows. Thepillars 385-3 and 385 a-3 strengthen the abutments 386 and 386 arespectively. This improves the strength and rigidity of the abutment,particularly in wider implants that have longer abutments and flanges.

Second component 381 of ISP 300 is shown in FIGS. 13a-13f . Secondcomponent 381 has a lateral bone anchor 381 a, the same as lateral boneanchor 181 a of ISP 200. Projecting in a superior direction from lateralbone anchor 381 a is bone anchor housing 382 c. Projecting in aninferior direction from lateral bone anchor 381 a is bone anchor housing382 d. Like bone anchor housing 382 a, bone anchor housing 382 d hassloped face 383 d, which was described above.

Axis X-X extends transversely from bone spacer 380, and axis X¹-X¹extends transversely from bone anchor 381. Those two axes meet whencomponent 380 and component 381 are mated to one another. This couplingof component 380 and 381 is achieved in the same manner as the couplingof components 180 and 181 of ISP 200, and ISP 300 can be implanted inthe same way as ISP 200 or ISP 30. When implanted, however, the inferiorend of ISP 300 (i.e., anchor assemblies 382 a and 382 d) is engaged tothe base of an inferior spinous process while the superior end (i.e.,anchor assemblies 382 and 382 c) is engaged to the posterior end of thespinous process just superior to the spinous process to which theinferior end of ISP 300 is engaged. Alternatively, ISP 300 is secured tothe last spinous process and the sacrum such that the inferior end ofISP (ie., anchor assemblies 382 a and 382 d) is engaged to the sacrumwhile the superior end (i.e., anchor assemblies 382 and 382 c) isengaged to the posterior end (or the laminal end) of the last spinousprocess in the vertebral column.

When stacking multiple ISP 300 implants, the order of implantation canbe superior to inferior as this would be the most convenient order ofimplantation. This is shown in FIG. 8a . For example, ISP 93 would beimplanted first, followed by ISP 92, then finally ISP 91. The superiorend of ISP 93 is engaged to the posterior end of the most superiorspinous process being treated while the inferior end is engaged to thebase of the spinous process just inferior to the spinous process engagedby the superior end of ISP 93. Then the superior end of ISP 92 isengaged to the posterior end of the spinous process to which theinferior end of ISP 93 is engaged so that the superior end of ISP 92 isposterior to the inferior end of ISP 93. The inferior end of ISP 92 isengaged to the base of the next spinous process. Finally, the superiorend of ISP 91 is engaged to the posterior end of the spinous process towhich the inferior end of ISP 92 is engaged so that the superior end ofISP 91 is posterior to the inferior end of ISP 92. The inferior end ofISP 91 is engaged to the base of the next spinous process. This can berepeated with additional implants.

The stacked implants can be connected to one another for added stabilityand to aid the process of fusion using connecting rods 94 and 95 asshown in FIG. 8b . Connecting rods 94 and 95 are connected to opposingsides of the implants. Extensions 96 and 97 that curve outward can beadded to the rods 95 and 94 respectively. Extensions 96 and 97 areconnected to one or more plates secured to the base of the skull whenthe implants are implanted into the cervical spine.

In FIG. 8c , a modified version of ISP 30 is used in which component 80is the same as in ISP 30, but component 81 is modified so that windows97 a and 97 b are replaced by zip-lock recesses 970 a and 970 b. Thestacked ISP assembly includes components 80 and 810, which mate with oneanother. In addition, there are a set of two rods 494. The two rods 494are the same with each having a stop 495 at each of its ends. One of therods 494 is assembled to components 80, while the other rod 494 isassembled to components 810. The rods 494 are held firmly in place withcouplers 500. There is a set of two couplers 500 for each ISP unit. FIG.8c depicts two ISP units, thus there are two sets of couplers 500 for atotal of four couplers.

As shown in FIGS. 8d-8f , coupler 500 has a smooth rounded dome 510forming its proximal end. Projecting transversely from dome 510 are twoopposing arms 520 and 530, each with a proximal rod support section 526and 536 respectively and an ISP lock section 528 and 538 respectively.The rounded dome 510 forms a circular rim 512 at its distal end. Rodsupport sections 526 and 536 extend distally from rim 512 so that arm520 is connected (or integrally formed) to rim 512 through rod supportsection 526, and arm 530 is connected (or integrally formed) to rim 512through rod support section 536. Rod support sections 526 and 536 areabout 180° apart from one another along the circular rim 512. Rodsupport section 536 has an upward cutout section 535. Cutout section 535forms a space between the rim 512 and the beginning or proximal end ofthe ISP lock section 538 that is sized to receive the rod 494. Thecutout section 535 receives the rod 494. Rod support section 526 has adownward cutout section 525. Cutout section 525 forms a space betweenthe rim 512 and the beginning or proximal end of the ISP lock section528 that is sized to receive the rod 494, and it receives the rod 494.Arms 520 and 530 are arched to follow the arc formed by the rim 512.Arms 520 and 530 are separated from one another by channel 540. On theouter surface of lock sections 528 and 538 are zip-lock teeth 527 and537 respectively. The teeth 527 and 537 are angled backwards, i.e.,towards the proximal direction toward the dome 510. The top or distalsurface of the teeth is sloped back, while the proximal or bottomsurface of teeth 527 and 537 are at about a 90° angle with the outersurface of their respective lock sections 528 and 538. Thus, teeth 527and 537 can slide forward through recessed holes, but cannot slidebackward back out of recessed holes because of the vertical face of theproximal or bottom surface of teeth 527 and 537.

Each of the lock sections 528 and 538 importantly have not just onetooth 527 and 537 respectively but a series of teeth 527 and 537respectively as shown in FIGS. 8c-8f . This is an important aspect,because the more teeth and corresponding recesses engage each other, thestronger the coupling that is formed. This is described and explainedwith respect to ISP 30 and ISP 200, and the same is true here withrespect to the couplers 500, which are required to form a tight, secure,and long-term rigid coupling of the rods to the ISPs. In one embodiment,each of lock sections 528 and 538 has 2, 3, 4, 5, 6, 7, 8, 9, or 10teeth. In one embodiment, lock sections 528 and 538 each have 5 teeth,and they mate with up to 5 recesses 970 a that receive those teeth onbarrel 970.

Rod 494 is inserted into multiple couplers 500 in the following manner.Rod 494 slides into a first coupler 500 through channel 540 until itrests against the rim 512. This is done with at least on additionalcoupler so that the rod 494 is coupled to at least two successivecouplers 500 along its length.

Once a rod 494 is coupled to at least two couplers 500, the at least twocouplers 500 can be coupled with the ISPs. This is done in the followingway. Rods 494 can be coupled to components 80 and 810 in any order with80 being first and 810 being next or vice versa. With respect tocomponent 80, couplers 500 with assembled rod 494 are guided towardsuccessive components 80 and the locking sections 528 and 538 of eachcoupler 500 are pushed through openings 80 c of each successive ISPunit. Locking sections 528 and 538 of each coupler 500 slide throughopenings 80 c of the ISPs. Teeth 527 come into contact with recesses 970a of barrel 970 of component 810. They slide into the recesses 970 a andare able to be pushed forward through successive recesses because thetop surface of the teeth are angled or sloped backward. The couplers 500are pushed forward until the rod 494 is squeezed tightly between therims 512 of each coupler and the center rings 80 b of each ISP. Theouter surface of center rings 80 b and that of rod 494 can be rough orribbed to maximize a friction lock between the rod 494 and rings 80 b.

On the other side of the ISPs, another rod 494 is secured to components810 in the same manner that rod 494 was secured to components 80. Once arod 494 is coupled to at least two couplers 500 in the manner describedabove, the at least two couplers 500 can be coupled with multiplecomponents 810 in the following manner. Couplers 500 with assembled rod494 are guided toward components 810 and the locking sections 528 and538 of each coupler 500 are pushed through openings 810 c of eachsuccessive ISP unit. Locking sections 528 and 538 of each coupler 500slide through openings 810 c of the successive ISPs. Teeth 527 come intocontact with recesses 970 a of barrel 970. They slide into the recesses970 a and are able to be pushed forward through successive recessesbecause the top surface of the teeth are angled or sloped backward. Thecouplers 500 are pushed forward until the rod 494 is squeezed tightlybetween the rims 512 of each coupler and the center rings 810 b of eachsuccessive ISP. The outer surface of center rings 810 b and that of rod494 can be rough or ribbed to maximize a friction lock between the rod494 and rings 810 b.

Before the rods 494 are firmly pressed against the ISPs by the couplers500, the couplers 500 are designed to allow some adjustability so thatthe rods are aligned properly with the ISPs. The teeth 527 and 537 havea certain width 527 y and 537 y as best shown in FIG. 8e . The width 527y and 537 y can be the same, but it is narrower than the width 970 ayand 970 by of the recesses 970 a and 970 b respectively. Thus, whenteeth 527 engage with recesses 970 a there is some free space betweenthe ends of the teeth 527 and the sides of the recesses 970 a. This islikewise the case with teeth 537 and recesses 970 b with which theyengage. The free space allows for the teeth to rotate within therecesses, and this allows the couplers 500 to rotate within the barrels970 about axis 500 x. This allows the rods 494 to tilt about arc 494 y.Cutouts 535 and 525 also allow rod 494 to rotate through cutouts 535 and525. Thus, the coupling system described herein allows flexibility toeasily adjust the rods before they are tightly secured in place.

Rods 494 have stoppers 495 so that if rods 494 do slip, they will notfall out. The rods can be coupled to two, three, four or more successiveISPs. Rods 494 can come in various lengths. The shorter length rods canbe used with two successive ISPs while longer rods can be used whenadditional ISPs are needed.

It is important that the rods be firmly secured and coupled to the ISPs.This is because the purpose of the rods is to minimize any movementbetween successive spinous processes. Stacking multiple ISPs and lockingthem together with rods provides the most rigid and non-dynamic means offusion between successive vertebrae. Thus, if the desired result isfusion between successive vertebrae, it is preferable to eliminate asmuch movement between the successive vertebrae that are desired to befused as possible. This aids the fusion process and hastens it. The rodscoupled to successive ISPs eliminates as much movement betweensuccessive ISPs as possible and thus locks successive spinous processestogether with respect to one another minimizing or eliminating anyrelative movement between those successive spinous processes. Thus, itis important to have a rod coupling system that is durable, long-term,convenient and easy to use while minimizing the risk of mechanicalfailure or slippage of the rods. The currently described zip-lockcoupling system ideally achieves these objectives for the reasonsdescribed above.

FIG. 9 depicts another embodiment of an ISP system that uses rods 117.The ISP system has an ISP 110 that has a component 111 and a component112. Component 112 has a barrel that slides into a corresponding barrelon component 111. The barrels use a zip-lock locking mechanism withteeth projecting out from the barrel of one of the components fittinginto teeth receiving recesses on the other barrel thus forming a lockbetween the barrels when the barrel of component 112 slides into thebarrel of component 111. Component 112 has arms projecting laterally ina superior and inferior direction. Component 111 also has armsprojecting laterally in a superior and inferior direction. One of thearms of component 112 has a nub 115 a, while the other arm of component112 has a hole 116 a with an offset section. The hole 116 a is sized toreceive the nub 115 a of another ISP 110. One of the arms of component111 has a nub 115 b, while the other arm of component 111 has a hole 116b with an offset section. The hole 116 b is sized to receive the nub 115b of another ISP 110. Extending transversely in an outward directionfrom component 112 opposite its barrel is a rod receiver 113 a that hasa channel 117 a that receives rod 117. The distal end of rod receiver113 a has a threaded section. Screw lock 114 a is screwed onto thethreaded section of rod receiver 113 a until it comes into contact withrod 117 and squeezes rod 117 firmly in place inside channel 117 a.Extending transversely in an outward direction from component 111opposite its barrel is a rod receiver 113 b that has a channel 117 bthat receives rod 117. The distal end of rod receiver 113 b has athreaded section. Screw lock 114 a is screwed onto the threaded sectionof rod receiver 113 a until it comes into contact with rod 117 andsqueezes rod 117 firmly in place inside channel 117 a. Multiple ISPs 110can be connected to another successively by coupling the nubs 115 a and115 b of one ISP 110 to the holes 116 a and 116 b respectively ofanother ISP and thus stacking two, three, four or more ISPs alongsuccessive spinous processes. Channels 117 a and 117 b of the additionalISPs 110 can receive the rods 117 so that the rods form a rigid complexof ISPs. The barrel of component 112 can spin or rotate slightly withinthe barrel of component 111 so that the direction or angle of the rodsalong the spinal column can be adjusted. Alternatively, rod receivers113 a and 113 b can rotate or spin about their axis independent of theirrespective barrels, thus allowing the direction or angle of the rodsalong the spinal column to be adjusted.

In another embodiment of the invention, an interspinous fusion implant(“ISP”) 1000 system is shown in FIGS. 10a-10f . ISP system 1000 isadapted for implantation in the cervical spine and is highly modular andcustomizable. System 1000 is adapted to be used on multiple cervicalspinal levels without the need for rods to connect successive implants.The components of the system 1000 include a barrel 1040 with anabrasive, roughened or ribbed surface finish to increases frictionbetween it and components attached to it. In addition to the barrel1040, there are hook members 1060 and 1061 that can be engaged with thebarrel 1040. There are also connection plates 1030 to connect multiplebarrels 1040 successively. In addition, there are screws 1020 thatsecure the plates 1030 to the barrels 1040.

ISP 1000 system is used in the following manner and is adapted to beused specifically in the cervical spine. Hook members 1060 and 1061 eachhave two regions. The first are barrel coupling regions formed by loops1065 and 1067 respectively, and the second are lamina coupling regionsformed by hooks 1064 and 1066 respectively. The loops 1065 and 1067slide concentrically over barrel 1040. The inner surface of loops 1065and 1067 can be abrasive, roughened or ribbed so that the loops 1065 and1067 form a secure friction lock with 1040. The inner surface diameterof loops 1065 and 1067 are sized to match the outer surface diameter ofbarrel 1040, so that the barrel slides tightly through the loops 1065and 1067.

Hooks 1064 and 1066 are adapted to engage the lamina of a cervicalvertebra. Hooks 1064 and 1066 can be angled outward away from each otherto match the angle of the lamina at its juncture with the spinousprocess. In one embodiment, hooks 1064 and 1066 form an acute angle α asshown in FIG. 10f . Angle α can be between about 60° and about 90°. Inaddition, the end of each hook 1064 and 1066 can be bent outward at anangle relative to a plane that is parallel with the barrel 1040 as shownin FIG. 10f . Angle can be between about 0° and about 60°, and in oneembodiment it is between about 30° and about 45°.

Two hook members 1060 and 1061 are engaged with a first barrel 1040 toform a first cervical ISP subassembly. The hooks 1064 and 1066 of thehook members 1060 and 1061 respectively are each bent at an angle awayfrom each other of between about 0° and about 60°, and in one embodimentbetween about 30° and about 45°, and in yet another embodiment at anangle of about 45°. Another two hook members 1060 and 1061 are engagedwith a second barrel 1040 to form a second cervical ISP subassembly.Again hooks 1064 and 1066 of the hook members 1060 and 1061 respectivelyare each bent at an angle away from each other of between about 0° andabout 60°, and in one embodiment between about 30° and about 45°, and inyet another embodiment at an angle of about 45°.

The two subassemblies are coupled together to form a cervical ISPassembly 1200 using lateral connection plates 1030. Each lateralconnection plate 1030 has a pair of adjacent holes 1033 and 1035. Hole1035 is circular and permits insertion of screw 1020 through it. Hole1033 is oval and elongated compared to hole 1035, and it also permitsinsertion of screw 1020 through it. Screws 1020 are threaded and matewith threaded holes in the ends of barrels 1040. Hole 1033 permits screw1020 to travel along the distance of oval hole 1033 when the screw isn'ttightened down against plate 1030. Barrel 1040 has ends that havethreaded holes in them that mate with the threaded screws 1020. Screws1020 are inserted through holes 1033 and 1035 of a first plate 1030 andfirst plate 1030 is held against the first ends of two adjacent andparallel barrels 1040 so that threaded screws 1020 align with threadedscrew holes in the first ends of the adjacent barrels 1040, and thescrews are screwed into the threaded holes. Then two more screws areinserted through holes 1033 and 1035 of a second plate 1030 and thesecond plate 1030 is held against the other ends of the same twoadjacent and parallel barrels 1040 so that the two additional threadedscrews 1020 align with the threaded screw holes in the other ends of theadjacent barrels 1040, and the screws are screwed into the threadedholes. Screws 1020 that are inserted into holes 1035 and are tighteneduntil the screw 1020 heads firmly squeeze the plates 1030 against theends of the first barrel 1040. The second set of screws that areinserted through holes 1033 are not yet completely tightened until thedevice is assembly is implanted. This allows for adjustment between thesubassemblies to account for each patient's unique anatomy and toaccount for the distance between successive spinous processes.

Once an ISP assembly 1200 is assembled, it can be implanted. Each barrel1040 of the assembly 1200 is inserted between two successive spinousprocesses. The first set of hooks 1064 and 1066 engage with the laminaof a first vertebra by hooking in a downward direction over the lamina.The hooks 1064 and 1066 each are at an acute angle that forms a gripover the lamina. The corresponding barrel 1040 rests between the spinousprocess of the vertebra to which the hooks 1064 and 1066 have engagedand the spinous process of the vertebra just inferior to it forming anabutment between the two adjacent spinous processes. The second set ofhooks 1064 and 1066 of the assembly 1200 engage with the lamina of thevertebra just inferior to the vertebra engaged by the first set of hooksin the same manner as the first set of hooks. The second barrel 1040corresponding to the second set of hooks rests between the spinousprocess of the vertebra to which the second set of hooks 1064 and 1066have engaged and the spinous process of the vertebra just inferior to itforming an abutment between those two adjacent spinous processes. Oncethe assembly 1200 is implanted the distance between the first and secondbarrels 1040 can be adjusted by moving the second barrel along the hole1033 until just the right distance is achieved and then screwing thesecond set of screws 1020 against the plates 1030 and forming a tightsqueeze between the plates 1030 and the second barrel 1040.

Another important feature of the assembly 1200 is that the hook members1060 and 1061 can be independently rotated about the barrels 1040 byapplying a strong force against the hooks 1065 and 1067. The independentrotation of each of the hook members 1060 and 1061 allows forsignificant variability in the implanted configuration of the assembly1200 within the cervical spine. It allows the implant assembly 1200 tobe maximally adaptable to the specific anatomy of the cervical spine ofthe patient who is receiving the implant. This is significant, becausethe vertebrae are not perfectly symmetrical, the lamina of the vertebrado not have perfectly predetermined shapes, and the distances betweensuccessive vertebra may be slightly variable. The adjustability of thehook members 1060 and 1061 through rotation about the barrels 1040 andthe adjustability of the distance between the barrels 1040 is thereforean important feature of the assembly 1200.

Another important feature of ISP system 1000 is its modularity. Themodularity of the system 1000 enables additional vertebra of thecervical spine to be engaged by adding additional subassemblies to theISP assembly 1200. The assembly 1200 can expand from two barrels 1040 asshown in FIG. 10f to six or more barrels 1040 as shown in FIGS. 10a-10e. Additional barrels are added to the assembly 1200 using additionallateral connection plates 1030 and threaded screws 1020 to screw thoseplates 1030 against the barrels 1040. Multiple plates 1030 on oppositesides of the barrels 1040 can be used to connect together up to six oreven more barrels 1040. As shown in FIGS. 10a-10e , in one embodiment, astack of six barrels 1040 are connected to one another. In oneembodiment, as shown in FIGS. 10a-10e , the hook members 1060 and 1061on the third and fourth barrels can be oriented to face each other. Thispermits those hooks (on the third and fourth barrels 1040) to engage thesame lamina from both the superior and inferior side of the lamina. Withtwo sets of hooks latched onto a single lamina from both the top(superior) and bottom (inferior) side, the risk of the ISP system 1000migrating or becoming detached from the cervical spine is minimized. Inaddition, the modularity of ISP system 1000 actually permits the hookmembers 1060 and 1061 to be turned to the other direction on any of thebarrels 1040. This feature of engaging the hook members 1060 and 1061 inthe opposite direction on the barrels 1040 allows the hooks 1064 and1066 to have the flexibility to engage whichever lamina is better suitedfor engagement. Thus, if the inferior lamina is stronger, forms a betterfit with the hooks 1064 and 1066 or some other anatomical feature makesit more suitable for engagement, the hooks 1064 and 1066 can be orientedon the barrel so that they are turned downward in the inferior directionto engage the inferior lamina. If, in contrast, the superior lamina isstronger, forms a better fit with the hooks 1064 and 1066 or some otheranatomical feature makes it more suitable for engagement, then the hooks1064 and 1066 can be oriented on the barrel so that they are turnedupward in the superior direction to engage the superior lamina.

Yet another important feature of the ISP system 1000 is that it does notrequire bone engaging screws or rods. This minimizes the size of theimplant and reduces both the incision and the amount of traumaexperienced by the patient at the implant site, thus shortening recoverytimes and improving patient quality of life. Without pedicle screws thatare screwed into the bone and rods connecting them, the trauma to theimplant site is significantly reduced.

Another aspect of the present invention involves bone growthstimulation. Pulsed electromagnetic field therapy (PEMFT), also calledpulsed magnetic therapy, pulse magnetotherapy, or PEMF, is a reparativetechnique most commonly used in the field of orthopedics for thetreatment of non-union fractures, failed fusions, congenitalpseudarthrosis and depression. In the case of bone healing, PEMF useselectrical energy to direct a series of magnetic pulses through injuredtissue whereby each magnetic pulse induces a tiny electrical signal thatstimulates cellular bone repair. It is believed that PEMF therapy causesbiochemical changes at the cellular level to accelerate bone formation.In 1979 the FDA approved non-invasive devices using pulsedelectromagnetic fields designed to stimulate bone growth. In 2004, apulsed electromagnetic field system was approved by the FDA as anadjunct to cervical fusion surgery in patients at high risk ofnon-fusion.

Recent technologies in the field of promoting spinal fusion includecapacitive coupling (CC) and combined magnetic field (CMF) devices. Bothtypes of devices are worn externally and are used for up to nine monthsafter spinal fusion surgery. CC stimulates a continuous biologicalresponse and is worn 24 hours per day. The device is made of two small,wafer-thin skin pads/electrodes that are placed directly onto skin overthe fusion site. The CMF device delivers a time varying magnetic fieldby superimposing the time-varying magnetic field onto an additionalstatic magnetic field.

What the current technologies lack are non-invasive means of direct bonegrowth stimulation precisely at the fusion site or orthopedicimplantation site. One embodiment of the invention that addresses thisshortcoming is depicted in FIG. 15, which shows a bone growthstimulation system using dual purpose implants. The implants are dualpurpose in that they have a primary purpose of stabilizing a diseasedskeletal region or replacing a bone or joint that has become irreparablyinjured. They also have a secondary purpose which is to aid instimulating bone growth. The implants can be of any kind. For example,in FIG. 15, an intervertebral body or cage 4000, ISP 30 and anartificial femur 3000 are depicted. The implants can also be pediclescrews, plates, joints, or any other orthopedic implants.

Each of these implants is adapted to aid in bone growth in the regionsin which they are implanted. Bone growth stimulation is achieved bymaking the implants of a specific material. Each of the implants is madeof pyrolitic carbon or are coated with varying depths of a pyroliticcarbon surface. Previous orthopedic implants have been made of PEEK,PEKK, carbon fiber, silicon nitride, titanium alloys, trabecular andother metals. None have been adapted to be made of pyrolitic carbon andadapted to aid or stimulate bone growth.

Pyrolitic carbon is a structural carbon coating that is most oftendeposited on high density, high purity graphite pre-form. Othersubstrate pre-forms can also be used such as high melting point metals.The surface of pyrolitic carbon can be polished to a high gloss wherearticulation or thrombo-resistance is required. Alternatively, thesurface can be left in an as deposited state providing some surfacetopography for bone and or tissue on-growth. Pyrolitic carbon is highlyconductive and highly diamagnetic, making it an excellent material toreceive a wireless signal, such as a radio-frequency or magnetic signalinducing it to emit a magnetic field.

As shown in FIG. 15, an external transmitter 2000 transmits a wirelesssignal to the ISP 30 (can also be ISP 200, ISP 285, ISP 300, system 1000or assembly 1200 or any other implant disclosed herein), interbodyvertebral spacer 4000 or femur implant 3000. Each of implants ISP 30(can also be ISP 200, ISP 285, ISP 300, system 1000 or assembly 1200 orany other implant disclosed herein), interbody vertebral spacer 4000 orfemur implant 3000 have a surface that is coated to varying depths ofpyrolitic carbon deposited on a high purity graphite pre-form or anothertype of high melting point metal. The wireless signal transmitted bytransmitter 2000 can be a magnetic frequency signal, a radio frequencysignal, or any other type of wireless signal that can be received byimplants ISP 30 (can also be ISP 200, ISP 285, ISP 300, system 1000 orassembly 1200 or any other implant disclosed herein), interbodyvertebral spacer 4000 or femur implant 3000.

For example, in one embodiment, the external wireless transmittercommunicates with interbody vertebral spacer 4000. Interbody vertebralspacer 4000 has dual functions. Its primary function is to be implantedbetween adjacent vertebrae and create space between those vertebrae. Ithas hollow openings into which bone growth material, such as syntheticor natural bone matrix, can be packed in order to aid in bone fusionbetween the two adjacent vertebrae. In addition, it has a pyroliticcarbon surface that can be smooth or porous. A porous surface willpromote bone on-growth on the surface of the spacer 4000. During normaluse it acts as a typical spacer. However, when it receives a wirelesssignal from the external transmitter 2000 the pyrolitic carbon surfaceacts as a conductor for that signal and it emits a magnetic field to theareas around it. The emission of magnetic field to the bone around thespacer 4000 stimulates bone growth of the native bone and enhances theactivity of the packed bone matrix. Thus, spacer 4000 acts as a bonegrowth stimulator and promotes fusion when it is activated by theexternal wireless transmitter 2000.

The system described above with respect to FIG. 15 provides asignificant improvement over prior systems that require external gearworn or placed on the skin to emit magnetic energy to skeletal tissue orremovable leads implanted in the body and that extend out of the body,which need to be extracted after fusion is complete. The present systemcan remain in the body long-term, reduces the potential for infectionsdo to leads extending out of the body, and eliminates the need forwearing bulky electromagnetic transmitters. In addition, devices likeISP 30, spacer 4000 and femur 3000 result in better and more efficienttransmission of magnetic energy to the immediate substrate. Also themagnetic energy is emitted from the entire implant and radiates out fromthe implant in all directions rather than a unidirectional externaltransmitter. This results in better, more uniform, and more completestimulation of the bone adjacent the implant.

In another example, the external wireless transmitter communicates withISP 30 (this description applies equally to ISP 200, ISP 285 and ISP300). ISP 30 has dual functions. Its primary function is to be implantedbetween adjacent spinous processes, create a space between them,stabilize the processes with respect to one another, and promote fusionbetween adjacent vertebrae. It has a hollow barrel (97 as shown in FIG.4) into which bone growth material, such as synthetic or natural bonematrix, can be packed in order to aid in bone fusion between the twoadjacent vertebrae. In addition, it has a pyrolitic carbon surface thatcan be smooth or porous. A porous surface will promote bone on-growth onthe surface of the ISP 30. During normal use it acts as an interspinousfusion implant. However, when it receives a wireless signal from theexternal transmitter 2000 the pyrolitic carbon surface acts as aconductor for that signal and it emits a magnetic field to the areasaround it. The emission of magnetic field to the bone around ISP 30stimulates bone growth of the native bone and enhances the activity ofthe packed bone matrix. Thus, ISP 30 acts as a bone growth stimulatorand promotes fusion when it is activated by the external wirelesstransmitter 2000.

Another problem addressed herein is that implants ideally should have amodulus of elasticity that is similar to the bone at the implant site.When an orthopedic implant is placed in the body to replace a bone or apart of a bone, it needs to handle the loads in the same way as itssurrounding bone. If the modulus of elasticity of the implant is muchgreater than the modulus of elasticity of the native surrounding bone,the implant will take over the load bearing and the surrounding bonewill start to decay. This will result in loosening of the implant andeventually ends in failure, the consequence of which is a revisionsurgery to replace the implant.

The present invention addresses the problem by providing kits ofimplants that contain varying ranges of modulus of elasticity. Theimplants used with the bone growth stimulation systems described hereincan be packaged so that each kit or package includes a series ofimplants that each has a different modulus of elasticity. Thus, the kitincludes implants of varying modulus of elasticity. The healthcareprovider can determine the bone quality of each patient by performing abone density scan at the implantation site and can then match an implantthat has the nearest modulus of elasticity to the native bone at theimplant site. In this way, the implant can be customized to match thebone density at the implant site of each patient, thus reducing the riskof reversion surgery.

For example, in one embodiment a kit can include the following implants,tools and materials: (1) an ISP 30 having a modulus of elasticity ofbetween about 5 GPa and about 15 GPa (e.g., about 10 GPa in oneembodiment); (2) an ISP 30 having a modulus of elasticity of betweenabout 15 GPa and about 25 GPa (e.g., about 20 GPa in one embodiment);and (3) an ISP 30 having a modulus of elasticity of between about 25 GPaand about 35 GPa (e.g. about 30 GPa in one embodiment). In oneembodiment, the kit can also include (1) an ISP 30 having a modulus ofelasticity of between about 35 GPa and about 45 GPa (e.g., about 40 GPain one embodiment); (2) an insertion/compression tool; (3) aremoval/splaying tool; (4) synthetic or natural bone matrix, such asbone matrix pellets; (5) a wireless signal transmitter; and (6)instructions for use. In another embodiment, a kit can have all of thematerials set forth above plus the following: (1) additional sets ofISPs 30 at each modulus of elasticity for the purpose of stacking ISPsfor multiple implantation; (2) rods (such as rods 494) for connectingthe multiple ISPs 30; and (4) couplers (such as couplers 500) forcoupling the rods to the ISPs 30.

In yet another example, a kit can include the same elements as set forthabove, except that each of the ISPs 30 are replaced with spacers 4000 inwhich each of the spacers has the same modulus of elasticity as the ISPs30 in the above described kit.

In yet another example, a kit can include the same elements as set forthabove, except that each of the ISPs 30 are replaced with a femur implant3000 in which each of the femur implants has the same modulus ofelasticity as the ISPs 30 in the above described kit.

While the invention is susceptible to various modifications andalternative forms, specific examples thereof have been shown by way ofexample in the drawings and are herein described in detail. It should beunderstood, however, that the invention is not to be limited to theparticular forms or methods disclosed, but to the contrary, theinvention is to cover all modifications, equivalents, and alternativesfalling within the spirit and scope of the appended claims.

We claim:
 1. An interspinous fusion device comprising: a first memberhaving a ring with two or more anchor assemblies projecting laterallyfrom substantially opposite sides of said first member ring, the firstmember further comprising a first flange and a second flange that eachextend transversely and from opposite sides of the ring, the two flangesfacing each other and biased toward one another, wherein each of saidfirst and second flanges comprises a series of teeth protruding inwardlytherefrom; a second member having a ring with two or more anchorassemblies projecting laterally from substantially opposite sides ofsaid second member ring, the second member further comprising a barrelextending transversely from the second member ring wherein the barrelcomprises a first column of recesses adapted to mate with the teeth ofthe first flange and a second column of recesses adapted to mate withthe teeth of the second flange, wherein the barrel has openings onopposite sides of the barrel in between the first and second column suchthat when the first member is mated with the second member there are noother mechanical components within the barrel such that an unobstructedpassage is formed through which bone graft material can extend; whereinthe first member is adapted to slide over the barrel of the secondmember such that the series of teeth of the first flange mates with therecesses in the first column of recesses of the barrel and the series ofteeth of the second flange mates with the recesses in the second columnof recesses of the barrel, the bias of the two flanges further causingthe two flanges to compress down onto the barrel to form a compressionlock with the barrel without the aid of a set screw, a pin, or othermechanical component.
 2. The interspinous fusion device of claim 1,wherein the second member further comprises a first bone abutment and asecond bone abutment, each of said first and second bone abutmentsextending transversely from the first member ring.
 3. The interspinousfusion device of claim 2, wherein each of said bone abutments has anopening formed on its respective surface.
 4. The interspinous fusiondevice of claim 3, wherein the barrel comprises a first opening and asecond opening on its surface, wherein the openings on the abutments canbe substantially aligned with the openings on the barrel when the spacermember is secured to the anchor member through the mating of the teethof the flanges to the recesses of the barrel such that a continuousopening extends through the barrel in which no other mechanicalcomponents are within the barrel.